OpenBSD version / build question

Hi List!

I'm upgrading a server from OpenBSD 4.1 to 4.2 and there are a number of servers that have been done already. 'uname -a' tells me that they are:

OpenBSD hostname 4.2 GENERIC#375 i386
OpenBSD hostname 4.2 GENERIC#410 i386
OpenBSD hostname 4.2 GENERIC#468 i386

375, 410, 468:
Are these build numbers?
Or do they mean something else?
Would they signify security fixes that are important?

Should I be concerned that they are not the same across our different servers if our goal is to keep a consistent setup?

Thanks,

Patrick Smith