Memory layout and the garbage collector (GC) differ significantly between the two implementations.
For the details see 11.3 Memory Management in 32-bit LispWorks and 11.4 Memory Management in 64-bit LispWorks.
The output of room differs between 64-bit and 32-bit LispWorks.
LispWorks® User Guide and Reference Manual - 01 Dec 2021 19:30:25