The words 'jakbyś' and 'gdybyś' have the same meaning. Bigger issue is with words 'jakby' and 'gdyby'. In some sentences you can use both words. 'Jakby było ciemno to zostałbym w domu' or 'Gdyby było ciemno to zostałbym w domu'. In this two cases 'gdyby' and 'jakby' we can translate as 'if'. But my advice is: if you want to use 'if' better use the word 'gdyby'. The word 'Jakby' we can also translate as 'something like'. For example 'jakby coś śmiedziało' means 'there is something wrong with the smell. It's not stink but there is some wrong smell'. 'Ktoś jest jakby łysy' it means someone isn't completely bald, he has some hair but not much and he is almost bald. I hope my explanation was understandable. If not please ask.

I wrote the answer in wrong place and I had to fix it :)