If you did not see the difference, it look like you have installed not the version I recommended - install
95RPP NOT the one from *here* (GOG). You can install 95RPP over GOG 95 version. It optionally can update nGlide in DOSBox directory to version installed in system, so install latest nGlide first and select update option in 95RPP then (otherwise it using shipped version).
You will see the difference just after start - it replace DOSBox with launcher-setup where more options are available (DOSBox.exe is renamed to BoxDOS.exe and it's started from launcher if selected). Also during setup many options are available. It also fix critical files - that crash game when unfixed in GOG release. So the *pack* contains also critical patches, when GOG "patch" add back only what they removed (plus wrappers), so it's not actually *patch*. If you need to access DOSBox configuratior (setting some options there can case DOSBox to crashing) you need to enable it during setup and then it's only available from launcher menu (shortcuts are not updated in this version yet, so it can't be launched from shortcuts - it may start, but will not work with this release).
(If you want even more fixes and options for customization in C1 - you can also install
Unofficial Carmageddon Patch)
OpenC1 it's not finished, so there are many not working things (like some cars, missing options, game rules etc.). It isn't working exact as retail C1, it's rather *very interesting* thing that require future work, than the full playable game.