There ideally shouldn't be, but here's a few I've seen:
In JapJi Sahib, the tuk of the first pauri that begins "chupai chup...", the papa in "chup" has a sihaari in the Taksaal gutkaa (which is correct), the Budhaa Dal (and others) one does not.
Budhaa Dal Chaupai and Rehraas is longer.
The rakhiyaa de shabad are longer too in the Budhaa Dal gutka.
The Budhaa Dal (and other Gutkas) have in general way more spelling mistakes than the Taksaal one.
In terms of other Gutkas, sometimes the mangals of the Baanis are different, especially in sawaiyaa and chaupai Sahib.
The Budhaa Dal gutka contains way more baani than any others.
I've even seen one Gutkaa app that puts the mangal before the sirlekh i.e. rather than "Ramkali Mahalaa 3 Anand Ik Oankaar Satgurprasaad", it says "Ik Oankaar Satgurprasaad Ramkali Mahalaa 3 Anand", which is a clear beadbi. Please avoid such apps and report where you can.
That's all I can think of at the moment...