Why are there 4 versions of installers?

You only need to install one of them. Maxima can be build using different Lisp implementations and the installers use different Lisp implementations.

Here is a comparison by running the test suite, result are sorted by speed:

maxima-sbcl-5.37.2
No unexpected errors found out of 10,357 tests.
Evaluation took:
86.938 seconds of real time
86.890625 seconds of total run time (82.796875 user, 4.093750 system)
[ Run times consist of 2.463 seconds GC time, and 84.428 seconds non-GC time. ]
99.95% CPU
17,594 forms interpreted
12,497 lambdas converted
348,446,725,113 processor cycles
23,701,921,648 bytes consed

maxima-gcl-5.37.3
No unexpected errors found out of 10,408 tests.
real time : 110.599 secs
run-gbc time : 104.629 secs
child run time : 0.000 secs
gbc time : 5.969 secs

maxima-openmcl-5.37.1
Error summary:
Error found in C:/Program Files (x86)/Maxima-openmcl-5.37.1/share/maxima/5.37.1/tests/rtest16.mac, problem:
(50)
1 test failed out of 10,357 total tests.
(TESTSUITE)
took 119,012 milliseconds (119.012 seconds) to run.
8,723 milliseconds ( 8.723 seconds, 7.33%) of which was spent in GC.
During that period, and with 8 available CPU cores,
115,453 milliseconds (115.453 seconds) were spent in user mode
2,937 milliseconds ( 2.937 seconds) were spent in system mode
17,175,463,902 bytes of memory allocated.

maxima-clisp-5.37.3
Error summary:
Errors found in C:\maxima-5.37.3\share\maxima\5.37.3_5_g8106b41_dirty\tests\rtest11.mac, problems:
(117 118 119 120 121 122)
6 tests failed out of 10,408 total tests.
Real time: 421.37137f0 sec.
Run time: 421.03125f0 sec.
Space: 23092633120 Bytes
GC: 7260, GC time: 44.609375f0 sec.