Prime interest rate and Rate of interest

Prime interest rate noun - The interest rate on short-term loans that banks charge their commercial customers with high credit ratings.

Rate of interest and prime interest rate are semantically related in interest rate topic. In some cases you can use "Rate of interest" instead a noun phrase "Prime interest rate", when it comes to topics like sum charged for use of money.

Rate of interest noun - The percentage of a sum of money charged for its use.

Prime interest rate and rate of interest are semantically related in interest rate topic. You can use "Prime interest rate" instead a noun phrase "Rate of interest", if it concerns topics such as sum charged for use of money.