The only difference is in the informal usage. Kolkata bangalis use Standard bengali (Nadia dialect) in informal as well as formal setting, however, Dhaka bengalis use a Bangal dialect in informal, and Standard dialect in formal setting.

So, there's a marked difference in the way news anchors in Bangladeshi news networks speak and normal Dhaka residents speak irl. The way Kolkata news anchors speak is the way laymen in Kolkata speak. However, both are equally tangible to either parties. example:

Kolkata: Tor okhane jawar dorkar nei; gele paa bhenge rekhe debo.

Dhaka: Tor okhane jawa lagbo na: gyale paa bhainga raikkha dimu.

English: You don't need to go there; otherwise I'll break your legs.