CPS2 had a processor that was 33% faster than the NeoGeo and pretty much double the RAM.
NeoGeo also had, if memory serves, a 320x244 resolution VS. up to 512x262 for the CPS2, along with 4096 colors from a 16 bits (65536) palette VS. the same 4096 on screen for CPS2 but from a 32 bits palette (16.7M colors).
There was also the 4KB of sprite RAM on the NeoGeo which compared to the 280KB for the CPS2 is so far, far away.
There was mainly clever memory management tricks to allow the NeoGeo to perform, like a direct access tilemap address range on the cartdridge and rendering across multiple scanlines (like Last Resort, which explained the slowdown and occasional bullet flickering)
Sound was widely different so it's hard to compare but I believe NeoGeo had embeded sound on the cartridges for the banks, while CPS2 was an all-around powerhorse DSP.
In short: I believe that there's no way in hell CPS2 games could have "as-is" ran on NeoGeo; it would have to be a port to accomodate the limitations (degraded graphics, sound, level size, sprite size, whatnot...)