Do you mean that you bought the mytouch 4g?If thats the case then no they don't know anything that you don't know. The g2 is a dev phone tho, and now that it has fully achieved root there will be a ton of custom roms and different tweaks for this phone. I'm sure the mytouch 4g will have some of the same roms and tweaks but it just wont have as many.
The g2 has no video calling, a smaller touch screen, and a key board.
The my touch 4g has no keyboard, a better bigger screen, and can video call from anywhere anytime.
If you like the mytouch4G then keep it. Its one of the best android phones you can buy.