so what is the difference between the 4.6, and the 5.4s, and the 302s and 351s of old. My cousin and I own 88 f150s, one with a 302 and a 351, and I'm kinda partial to those motors(rebuilt several 302s).
How do these motors compare and why did they move away, and are the new motors better?

 

The new 4.6s (281) and 5.4 (332) are overhead cam motors or "modular" motors. Thats the main difference. Also, the fuel injection system is different.

Good info below

 

Stock for stock, the latest generation of modular motors makes more power (4.6L vs 302, 5.4L vs 351, V10 vs 460).

Once you start the modification process, the old saying about cubic inches give the Windsors/385 the advantage. The Windsors and 385's are also much cheaper to build.

EDIT: The 5.4L does not displace 351cid...it's a 332.