A500 runs with 512K Chip Ram, OCS chipset and usually Kickstart/Workbench 1.3
A500+ runs with 1Mb ChipRam, ECS Chipset and Kickstart/Workbench 2.04
Select About from the Workbench menu for versions
1.3 = 34
2.04 = 37/38
Showconfig or Sysinfo type programs will give more information.