Hey I just started learning on the alto sax, but want to switch to the tenor. Just wondered what the biggest diffrences are and if its a difficult transition.

I started sax on alto and switched to tenor with ease. The only differences are the size, the amount of air you need to support, and a slight embouchure change. Overall it's not a hard transition. I love the sound of tenor sax, so good luck.

the biggest thing i was confused about is on fingering charts the notes are the same for alto and tenor... but they are diffrent keys. so i don't see how they could be the same note on the same finger positions?

Saxophone is a transposing instrument, meaning that if we play a note it will not be the same in concert pitch. Adolf Sax did it this way so there would be an easy transition between the saxes, and you wouldn't have to learn new fingerings.
Alto and Bari are Eb
Soprano and Tenor are Bb
This translates to when you play a C on a tenor it sounds like a concert Bb and when you play a C on an alto it sounds like a Eb.
That being said alto and tenor music are not interchangable (unless it is unaccompianied) and you will have to transpose. That is why there is always separate music for alto and tenor.

Exactly. I learned this the hard way. I was per forming a solo with a piano last year, thought it would be cool to play it on both my alto and tenor. The piece was meant for Bb Tenor, not Eb Alto. At the time, i didnt know the difference. So when i got to the repeat, i picked up the alto and started playing.

I think you see where this is going.

going from a sax to a tenor is just the same notes as a sax's notes....but the tenor has a deeper voice then the sax does...

fingurings are the same you fingure a G on the tenor the same way you do on an alto. They're just in different concert pitches.