compendium equal to books?

hey im thinking of getting tavlas guide to everything, but im not sure if i should get the book or get it on here?, is it the same but i can just auto add stuff on my compendium as well?

The reading experience is probably more enjoyable in the paper form. The advantage to getting it on Roll20 is the drag and drop and Charactermancer features.

ah, does it not have a pdf version? that i can read online?

No, it does not come with a pdf.  I find the hard copy excellent for planning.  The Roll20 copy is a good reference when in game and need to find something quickly.  Depending upon the compendium, the conversion into Roll20 may not be complete in that all the information is there, but some of the functionality, mostly around certain tables or sometimes artwork tokens, is not fully realized.

Usually most of the info can be read sequentially from the book link at the top of the Compendium Page , but things like spells and monsters (drag and drop items can be broken out. But every scrap of text is there.