In the USA all purchases of either kind are logged now (maybe not the primetine tabs that have 12.5mg of ephedrine + 200mg of guiafenishit and a much higher price tag)
Pseudoephedrine is the good sudafed/generic equiv. Don't ever buy the new "Sudafed PE" with phenylepherine; it's useless as a decongestant - it was only introduced under DEA pressure (since you can't make meth with phenylephrine). Studies have frequently questioned it's effectiveness, with many failing to find an advantage over placebo. Ask at the counter for the good stuff if you actually want a decongestant that works. It does not produce a high of any sort.
Ephedrine is a stimulant (mostly physical, but it produces a noticable increase in energy. Lousy high, but it's the best OTC, non RC stimulant I think), which is an excellent bronchiodialator. Very helpful for asthma sufferers, particularly in combination with guiafenisen.
The two differ only in the chirality of the beta carbon - amazing the difference that can make eh? Both are usable interchangibly for purposes of making meth.