Yes there is a clear contrast. However, each can vary by dialect. Roughly, you usually get a /v/ for bh in leibh and a /t/, or possibly an /ht/ for the t (but make sure your tongue touches the front teeth, as in English th).
One of the good things about Gaelic Duolingo is that you can hear lots of different real people pronouncing this words if they have been catalogued. Unfortunately, these words haven't - I checked, but perhaps one day.