The product "A" and "B" formed in above reactions are :

The explanation is,

In the first reaction carbocation is formed since the medium is acidic in nature the OH group is lost in the form of water molecule, it follows satzeff rule and more substituted alkene is formed as major product.

Whereas in reaction 2 the reaction is controlled by the size of the base, the base is bulky and elimination is controlled by stearic course or reaction and less substituted alkene is formed as major product obeying Hoffmann elimination reaction.