Space and The Web vs. Time and The End
Space and Time are the two 'basic fabrics of paradox space'. They represent creation and destruction, and are fundamental to reality.
The Web and The End are the only two entities not to have a specific ritual of their own: they benefit no matter what the world is like.
Space and The Web
Space is concerned with where things are and how fast they are going: the size, dimension, and velocity of all things. The Web is concerned with where people are and what they are doing. They both see the 'big picture' and aren't focused on minute details; as long as things are where they need to be, they're happy.
In Homestuck, Space is concerned with the Genesis Frog and creating a new universe. In The Magnus Archives, The Web is concerned with marking The Archivist so that the Entities can move to a new universe.
Time and The End
Time is concerned with timelines continuing or dying, and overall it has a heavy emphasis on death or destruction. The Scratch is used to destroy the players' current session, and Time players like Dave, Caliborn and Aradia are all connected to death in some way. The End is concerned with lifetimes continuing or dying. It revolves around the idea that all things will come to an end eventually.
Time is also concerned with repetition - the beat of a song, or the turn of a cog. The End is related to repetitive concepts as well: death itself will keep happening no matter what, and the entity itself has close ties to dreaming, something that happens every time we fall asleep. There is literally a concept called circadian rhythm.
The Web and The End are opposites in this system as The Web is about 'doing things', while The End is about 'not doing things'.
They both also have links to fate - The Web's concept of 'free will vs. fate' and The End's idea that everything is fated to die eventually.