I was trying to look up the definition of tessitura, and it seems as though it refers to the range within which most notes fall in a piece. I thought this was what range was though? or are they the same thing?
Yes, "tessitura" is a posh term meaning "range".
As always, niceties can be discovered. An individual singer has an overall range, outside which he CAN'T sing. But he will generally be able to sing a particular song in several keys, without exceeding those limits. We might say he can use a higher or lower "tessitura" within his "range".
The difference between tessitura and range is distinct. The range is the lowest to highest note, either of the piece, or the pitch at which one can comfortably sing, or play on the instrument in question.. Tessitura is the general position, most used register, or lie, of the vocal lines.If a piece has a lot of high parts, that may well tax a singer's vocals, the high tessitura is what's mentioned when talking about it. It will also influence which clef is used for certain instruments. Thus a piece can have a high or low tessitura. Seems to have more bearing on the pitch limits of a piece than those of the vocalist.