In Autocad when we use HATCH and when we use BHATCH ?

Hatch:

Within one or many closed boundaries, a cross-hatch pattern may be created with the Hatch command. The boundaries must be well-defined, otherwise, the cross-hatch may leak out unexpectedly. The user may select pre-determined patterns supplied by AutoCAD, or they may enter their own and add them to the set that’s already there.

Bhatch:

A newer command in the AutoCAD quiver, it helps the user to better use as compared to Hatch command. It supports boundary hatching, allowing the user to pick a point that is adjacent to the boundary they wanted, and this new command lets AutoCAD search for the nearest entity, then constructs a closed boundary by tracing in a counterclockwise fashion to look for intersection points as well as connecting lines or arcs. Bhatch is convenient in that it allows the user to preview adjustments without having to start over each time.

In short, BHatch is replacing Hatch to better use.

hatch are commonly used in closed loop or object and bhatch like the word itself defines the boundary and make a hatch.

HATCH is used to fill a closed loop with a pattern or gradient, whileBHATCH is used to identify an open boundary for filling, which is not possible while using the regular HATCH command.According to Autodesk, the command BHATCH has been renamed to HATCH.

BHATCH Command has been renamed as HATCH.

If you type BHATCH Command will see same HATCH Command box....

nice quistion and helpful answers

Both BHATCH and HATCH used when example; Wall Section

Please see Autodesk.com

Fills an enclosed area or selected objects with a hatch pattern or gradient fill.

AutoCAD 2010 User Documentation: BHATCH - Autodesk