[DINKDINK]

>how do these users vote?

Simple, by running which ever client that has the consensus rule set they want.

>how are they different from miners?

Miners use hashing power to produce blocks that meet users' consensus rules. Users verify these blocks meet their own consensus rules.

e.g. HashingCo uses their miners to produce a block with a blockreward of 12.5 bitcoin. In that block they include a transaction to their power supplier. The power supplier receives the block over the p2p network, checks if it is valid for their consensus rules, and then settles their bill. If HashingCo produces a block with a 100 bitcoin coinbase reward, sent that block to their power supplier, no amount of hashing will get their supplier to accept it as valid