Yes, they're all compatible with each other.
The 38-subcode (aka privacy codes) on some models don't prevent any other FRS from hearing what comes from one with the subcode on. If you're using channel 10, subcode 18, anyone tuning in channel 10 without a subcode selected or available can still hear you.
They only permit you to screen out incoming FRS transmissions on the same channel that either don't have a subcode, or aren't using the same subcode on your channel. It's helpful when there are a lot of FRS users in the area and you're hearing folks you don't want to.
In short, it is an incoming filter, not an outgoing "scramble" feature.
Brent
_________________________
Tip: see if your question has already been answered before asking it. Try our handy-dandy search tool!