what exactly is the diff. in an ls1 and an lt1 engine...thank you

LT1/LT4
Based on original small block Chevy. For Camaro use is has cast iron block, aluminium heads, reverse cooling system, shaft driven water pump, distributor mounted on timing chain cover, camshaft driven oil pump, 2 bolt main bearing caps, sequential FI, short runner intake manifold.

LS1
Entirely new design. Aluminium heads & block, standard cooling, georotor oil pump driven directly by crankshaft, evenly spaced intake and exhaust ports, no distributor, coil on plug ignition, 6 bolt cross bolted main bearing caps, sequentila FI, composite material intake manifold.

There are very few parts interchangeable between engines. In genera,l the LS1 produces more power due to better head design.