3rd gen has :-
1- Different style of intake manifold
2- has CKP sensor inside the timing belt cover (although you can see its wiring harness coming out of the timing belt cover, just above the alternator)
3- has coils mostly, some models also have distributors but they are not adjustable & the distributor has single wiring harness (same in mine 7a), whereas older ones were adjustable and had 2 wiring harnesses.
Re-uploaded the above pic.
These are some main things, which will help you differentiate between different gens.