shatabdi express has ECC called Executive chair car ..with additional legroom and space and more comfortable seats including a different menu and some additional tidbits...
1A is the highest class available on indian railways train. it has both seats as well as berths to sleep on unlike the ECC in shatabdi in which u can only sit....
for convenience IR keeps ECC and 1A in the same category.....though both are completely different in their layouts......1AC is found in almots all premier trains and surely on Rajdhani and AC exp and AC Duronto express...
more... which have overnight journey.....