I currently fly E190 but have flown also E170 couple of years ago. There are very few differencies between different versions. Most of them being quite obvious as already mentioned.
E190 has tail strike protection fitted in fly by wire system. Also there are very small differencies between flap settings. Flaps 1 on E190 is 7 degrees while on the E170 it is 5 degrees. Flaps full on E190 is 37 degrees compared to 35 degrees on the E170. From pilots point of view this is not very relevant since flaps are operated by positions like in an Airbus.
Takeoff flap positions on the E170 are 1/2/4 while on the E190 position 3 is also available.
Also there are three external emergency lights on each side of the fuselage on the E190. These are of course due to overwing exits which are not required on the E170.
There is one additional smoke detector fitted in the cargo hold on the E190 (4 in FWD and 3 in AFT).
There are some differencies in limitations like gear speeds, max brake temps for takeoff, engine limits, fuel etc. Performance wise it is quite interesting that required landing distance is almost similar eventough max landing weight is approx 10 tons higher on the E190.
I think on E170/175/190/195 most differencies come from the equipment and software installed. There might be different avionics software or different fadec software installed. Also there are several optional equipment like airstairs, HUDs, autobrake etc.