What is the difference between newly created bitcoin and transaction fees?

Detailed explanation

Revenue from a found block can have two components. The block subsidy is new issuance allowed by the protocol. It increases the bitcoin issued so far and decreases under the defined halving schedule.

Transaction fees work differently. A Bitcoin transaction uses existing inputs and creates new outputs. If the output sum is smaller than the input sum, the difference can go to the block's miner as a fee. No additional bitcoin are created; existing satoshis simply change who is authorized to spend them.

The two components together are often called the block reward. This can be confusing because only one part creates new units. Fees are also not automatically halved at a halving. Their level depends on factors including demand for block space, transaction size and miners' selection decisions. Fees become more important over time as the subsidy gradually decreases.