Are legato and slur one and the same? If the two are different, how do I tell which the piece is using? I know the gist of them (as opposed to staccato) but I need to know the specifics. They are notated the same (I believe). I am speaking of a wind instrument. Does this make a difference in the way they are played?
Legato is a technique, whereas a slur is a marking. As for what a slur denotes, Wikipedia does a pretty good job of handling the distinction between that and legato (see Slur and Legato). The most relevant quote from the legato article:
Legato technique is required for slurred performance, but unlike slurring (as that term is interpreted for some instruments), legato does not forbid rearticulation. In standard notation legato is indicated either with the word legato itself, or by a slur (a curved line) under the notes that are to be joined in one legato group.
The slur article notes that with some wind instruments, you should play each slurred note without using the tongue to rearticulate the note.