Offer your insights or judgment on the input financial query or topic using your financial expertise. Reply as normal question answering

Difference between a mortgage and buy-to-let in UK
Residential mortgages normally explicitly state that the property cannot be let without explicit permission, whereas BTL mortgages typically require that the property be let. There are other differences. Residential mortgages are regulated, which means that consumers have a degree of protection from mis-selling; most BTLs are not, as landlords are expected to know what they're doing. Affordability of residential mortgages are based on your income, since that is how you are going to pay for them. BTLs are (mostly) assessed based on the property's rental income, since it's that that will fund the mortgage. Finally, residential mortgages are typically done on a repayment basis, so that at the end of the term, you've paid off the entire loan, whereas BTLs are typically interest-only, on the assumption that you'll either sell the property, or remortgage, at the end of the term. (I've used words like "typically" a lot to give an overall picture of the differences. Obviously it's a bit more complicated than that, and there are exceptions to a lot of the above descriptions.)