Fun Fact: Goku fights smarter. Vegeta fights harder.
As a martial artist, Goku's developed and cultivated his skills over the course of his life, mastering a variety of creative techniques and, more importantly, honing his mind. A quick-thinking and analytical counter-fighter, Goku prides himself on a creative and clever dismantling of his adversary's capabilities.
This is where Goku excels as a fighter. He's a formidable martial artist in his own right but when pressured, he falls back on a generally high understanding of violence and a creative mind for opening solutions. He reads his opponent's style and abilities, finds its weaknesses, and exploits them.
This, incidentally, is part of what what made Majin Buu such an insurmountable hurdle for him.
Majin Buu is a taffy monster made of magic who defies even this universe's conventional physics. He has no fighting style; He just does things, and his infinitely regenerative body and supreme liquid flexibility leaves no weaknesses to exploit.
He cannot be fought the way Goku fights.
For his own style, Goku has one particular signature technique and a couple other moves he's picked up from others. His mainstay is the Kamehameha. But he's innovated a wide variety of ways in which the Kamehameha can be used, based on the needs of his situation.
Goku's used the technique in a variety of ways, such as using it for propulsion instead of as an attack.
Bending it around the opponent's defense for a surprise attack.
Making stationary torpedos that he can fire at will to startle and disorient his adversary.
The coolest attack in Dragon Ball history YES I SAID IT. Learning to teleport? Cool. Kamehameha? Cool. Teleporting in while charging the Kamehameha in order to throw it directly under your opponent's guard before he even has an instant to react? Top-tier.
Point is, this is who Goku is as a fighter. Brilliant and innovative, bringing a great deal of cleverness and creativity to his fights. He breaks down his opponent's technique and adapts himself to the needs of the situation at hand.
Vegeta is also highly observant and analytical. Do not mistake me for calling him stupid. He makes plans of his own, and his greatest asset is his ability to follow everything happening on the field at once. It is next to impossible to get the drop on this man.
Vegeta is always paying attention. He splits his focus incredibly well and quickly interprets what he's seeing and hearing with a critical eye. He misses nothing.
He is. Always. Paying attention. The one time someone actually managed to get the drop on him - and I cannot stress this enough - it was a person Vegeta did not know existed because he had not been a part of this battle up to this point.
Am I saying that Yajirobe's cowardice saved the world by not revealing his presence to Vegeta until this fateful moment? Yes. Yes, I am saying that. We literally have a counter-example from someone Vegeta did know and account for to contrast it with.
Vegeta is always paying attention. Unless he doesn't know you exist.
So. Yeah. Vegeta is incredibly brilliant and observant. But what he's not is a martial artist. Vegeta, instead, is a soldier. He's comfortable in the realm that overwhelming power creates.
He hits very, very, VERY hard.
In fact, Vegeta hits harder than Goku does. That's not to say that Vegeta is stronger than Goku; Vegeta and Goku go back and forth on who's stronger in the given moment over the course of the series. But Vegeta's attacks are stronger than Goku's.
To understand what that means, you need to understand that certain kinds of ki attacks have a multiplying effects on their user's strength. Attacks such as the Kamehameha or the Makankosappo, which concentrate ki before firing it, produce a much greater level of ki than their user's standard power output.
When charging a Kamehameha, Goku's battle power reading on the Scouter rises dramatically. This is the secret of techniques like the Kamehameha: they concentrate ki into a point before releasing it all at once, like pulling the pin on a grenade.
As concentration moves go, the Kamehameha isn't actually that great. The versatility and creativity that Goku brings to it is what makes it so formidable. Pound for pound, it kinda sucks. Piccolo's Makankosappo here makes the Kamehameha look like noob shit.
This kind of ability is non-standard among ki attacks, which are typically like throwing long-range punches. In fact, it's super-rare among the Planet Trade to be able to do this. Raditz had never even heard of a move like this.
Vegeta had. He knew of exactly one.
I am so sorry to do this to you but we're going to have to talk about battle power numbers here for a moment. Vegeta's clocked at 18,000 BP as of his battle with Goku on Earth; it's brought up a few times in the Namek arc.
Goku, iconically, is OVER 9000 8000!!!
At the moment Vegeta and Goku's attacks meet, Goku is channeling the Kaio-ken x3 which is exactly what it sounds like. He's inflated the ki inside his body to 300% capacity. The drawback is that his body is now an overinflated balloon ready to pop at any moment from all this swelled and bloated ki inside of him. But the gain is that he's outputting 300% power.
At this point in time, Vegeta has a battle power of 18,000. Goku, formerly >8,000 is now >>>24,000. Goku, further, is using the Super Kamehameha rather than the regular one he used against Raditz, which brings with it a higher level of power multiplication.
Nonetheless, the Galick Gun is winning against the Super Kamehameha. Goku is forced to resort to a x4 Kaio-ken - which does leave his body utterly destroyed and incapable of continuing the fight - in order to have enough power to overcome a superior magnification from a weaker opponent.
We see another direct comparison between the two in the Cell arc. That killer Warp Kamehameha fired point-blank into Cell when he least suspects it, which hits him dead-on and unloads its absolute maximum power into him? It does this.
Brutal. If Cell didn't have both Frieza's ability to survive ludicrous levels of harm and Piccolo's regeneration, it would have been over right here. Meanwhile, a glancing blow from Vegeta's Final Flash left him looking like this.
Despite Vegeta being far less powerful than Goku was when he fired that move, the effect is about the same - With implication that if Vegeta hadn't pulled the Final Flash back at the last second to avoid destroying the Earth, he would have erased Cell completely.
Goku's shot hit Cell point-blank and full-on to do about as much damage, albeit with deadlier aim in terms of killing a humanoid being.
This is the distinction between Goku and Vegeta as fighters. Vegeta is very smart, and Goku is very strong. Neither of them is lacking in intelligence or power. But they are philosophically very different fighters.
Pound for pound, Vegeta's moves hit harder than Goku's. He is the unparalleled master in taking the power he has and channeling it into as much destructive force as humanly possible.
On the flipside of that coin, when backed into a corner, Vegeta falls back on outputting as much direct force as he can. Goku gets to thinking his way around the problem at hand and devising a creative answer.
Goku is a surgical scalpel. Vegeta is a warhammer.
