Both share the same 1.5" aperture, same bolt pattern, same diaphragm, same flux in the gap, but the 2452 only weigths 2kg whereas the 2450SL wigths more than 4kg.
The 2452 core looks like a lower price evolution of the 2450SL/2451 core.
2450SL:
2452SL (pictures from Zilch):
For one thing, the back cap looks smaller, and the damping pad is also much smaller.
Any idea on what was given up during this transformation?
Low freq extension? (not really useful anymore with these rapid flare deigns)
Flux "stability" ? (if that makes any sense)
It is interesting to note than JBL came back to the older bigger design as the root of the 476 core: