The main difference between a register and a counter is…..

Answer: register has no specific sequence of states

There are two types of sequential circuits that are solely constructed from the flip flops – Registers and Counters.

A register is a group of flip flops having a common clock signal and capable of storing or retaining binary information. The register is mainly used for storing and shifting binary data entered into it from an external source.

A counter is a register that goes through predetermined sequence of states. While register has no specific sequence of states expect in certain specialized applications.