While his V3 is, like many other Vocaloids out there, advanced in his internal and external mimicry of the human form, V1 really is less so. One of the very first serious android productions made to resemble humans, he was, at the time, state-of-the-art, but, as with most technology, quickly became outdated in the span of just a few years. He's best likened to more fluidly moving and realistic version of this type of robot. He thus possesses all facial muscles needed to produce any expression humans are capable of, but he does not have the capacity to cry or produce tear fluid. He also does not bleed when cut or broken: his synthetic skin sits right over his wiring, so that is what will show should he scrape himself open. This means he is neither capable of blushing: there is no underlying redness to his skin that would allow him to do such.
The above video is also because covers a part of robot aesthetics also applicable to him: the use of certain facial structures for different genders.
As Crypton has mainly released female voicebanks, therein lies their specialty, and with the upgrade of their VBs from simple programs to corporal forms with voices, they also gained great skill at female body development for androids. Men, however, they were much less apt at. At Rin's and Len's age, the distinction between women and men was much lesser, leaving KAITO to be the only one that needed to get a very definite ' male ' shape. While Crypton's incompetence at actually produced male bodies never got as far as it did in the sprites for the ( early ) Project Diva games ( where reused modelling made for very feminine hips even where they should not be ), it did end up shining through in KAITO's facial built. Despite needing to market him, the company did their best to save expenses on his product due to him initially being deemed a failure, meaning that ( as with Android-F from the video ) they recycled. Thus, aside from subtle differences ( thicker eyebrows, less full and colored lips, etc. ), KAITO V1's facial structure is virtually the same as the then already created MEIKO V1's, as is visible here [ pdf2nd screencap ].
For V3, him being a person completely separate from V1 KAITO [ source ], the skeleton and skull were rebuilt from scratch so as to give him a completely unique appearance at last, a project Crypton now was willing to fund in their belief this model would succeed. V1 might, in looks, thus be more similar to his female counterpart than to his updated ' brother ' .