The coinbase (newly created coins) are a subsidy because the protocol is giving "financial assistance" to miners at the expense of inflation.

The fees are just fees.

Together, the block subsidy and transaction fees make up the mining reward that miners receive as revenue.

The whitepaper defines it as incentive:

6. Incentive

By convention, the first transaction in a block is a special transaction that starts a new coin owned by the creator of the block. This adds an incentive for nodes to support the network, and provides a way to initially distribute coins into circulation, since there is no central authority to issue them.

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The incentive can also be funded with transaction fees

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Once a predetermined number of coins have entered circulation, the incentive can transition entirely to transaction fees and be completely inflation free.

Revenue?