The guitar (and similar stringed instruments) is different than a keyboard in that there are many different positions (you can call them scale positions if you like) where you can play the exact same notes in the same octave. On a keyboard instrument such as piano, there is only one key per note and only one place where any given tone can be played.
Guitar tab is nothing more than the authors depiction of how they recommend playing a piece. Two versions of tablature for the same song may reflect the same notes but show them played in different positions on the guitar neck using different strings.
But two tabs by two different authors may also reflect different ideas on which notes to play in contrast with where to play the notes. Most tabs on the internet are simply someones interpretation of how they believe a particular work should be played or could be played on guitar. Each guitarist who takes the time to write out their interpretation of the best way to represent a particular musical work by a composer, on guitar, may have a different (not necessarily right or wrong) opinion on the best way to play a particular song or piece or musical work.
Also, there are varying degrees of complexity that can be conceived for a guitar arrangement of any piece of music and differing tabs may reflect different levels of difficulty. One could be a simple arrangement of the primary melody of the song while another may attempt to incorporate a bass line to go along with the melody line.
If you want to learn to play a song by using tab, try several alternate versions until you discover (through trial and error) which one sounds best to you and matches your current skill level and comfort level.
In the process of trying out other guitarists tabs, you may invent a new way to play the song that you like even better or that is easier for you to play. If you do, you can transcribe your interpretation (version) of the piece or song into your own tablature and even share it on line for others to see.
Have fun continuing to learn and improve your skills.