Senior debt typically has a floating interest rate. Types of senior debt include revolver and term loan. A floating rate means the interest rate is is based off of a benchmark rate (such as 1-month SOFR) plus a spread of usually 400-500 bps (4-5%).
Junior debt typically has a fixed interest rate. This means the interest rate does not change throughout the term of the debt. The interest rate is usually quite high given the increased riskiness of junior debt, usually around 12 – 17%.