I've only been playing a couple of months, and i've noticed that when I look at some tabs the finger positions that it says are much different than the ones I know. For example if it has a D chord on there instead of the way you play it at the top of the neck it has a way to play it that is much further down the neck, but when I play it it doesn't sound like the D I'm used to. Is it supposed to sound the same? I wish I could think of a specific tab to give an example but I cant.
Yes and no. The pitch is the same, but the timbre is different due to it be played on different strings. From my own memory of starting out, it seems that in the earlier days, timbre plays a bigger role than pitch in how something sounds. It's not like later on they sound the same, but it's like your brain can separate the sound of the different timbre from the pitch - you hear the difference in the timbre, but you also pick up the essential "D-ness" (in the case of your example) of the chord regardless of the voicing.
it was probably referring to a bar chord. yes they should sound the same note-wise because theyre the same notes just on a different place on the fretboard. it may sound a little different tone-wise tho since its not open strings
There are multiple chords that are the same all over the neck
the will be in theory the same chord, but as you say they are in a different position with more or less strings, they will sound noticably the same chord but slightly different phrasing. ie an open d chord uses 4 strings if you play it the standard way but an a shape barre chord at the 5th fret which is also a d will sound slightly different a fuller sound in a way.