My guess is that standard refers to all RFC OIDs?? MY understanding of which is that these OID's high up the MIB tree should be supported on all devices (is this just where the vendor decides it'll support it? It's not mandatory?) then the private MIB walk is walking the tree below the point where it becomes proprietary? So what I take from that is we should probably see a lot of OIDs that'd be supported across many different machines on a standard MIB walk but this would not be the case for a private tree walk because these would have been developed by the vendor unilaterally?
For a bonus point is there any difference between an SNMPwalk and a MIB walk? 2 tools performing the same job named differently by Solarwinds?