There isn't really any such thing as a B2 mechanical!!??
B1 is mechanical. "Roughly" equivalent to the old A&C
B2 is avionic. "Roughly" equivalent to the old X&R
There is now a crossover/overlap and a FULL B1 has FULL electrical certification rights.
A FULL B1 course SHOULD therefore be the equivalent of the old A&C but will include the electrical portion of the old X&R course (more or less)
A B1 can certify for structural repairs, inspections, EGR, just as any other mechanical licence provided the work is carried out IAW the correct relevant data.
However ALL this information can be found on the CAA web site.