night and day diffrences...as far as if u r talking about the old 1970 boss 302
it came with 4 bolt mains, steel crank,forged rods and pistons, heads were hugeeeeeeee canted valves..........2.19/175 exhaust, solid cam, buddy bar intake, holley carb.
I guess the dirrence would be the same as the diffrences between a windsor and a cleveland......if i missed something somebody will fill in the blanks.
as far as the new ones not sure haven't really looked at but i know it has siamesse block