Operating costs and Operating expense

Operating expense and operating costs are semantically related In some cases you can replace phrase "Operating expense" with "Operating costs", this phrases are similar.

Operating expense noun - The expense of maintaining property (e.g., paying property taxes and utilities and insurance); it does not include depreciation or the cost of financing or income taxes.

Operating costs and operating expense are semantically related in money needed to run a business topic. You can use "Operating costs" instead a noun phrase "Operating expense".