There is a difference. These two words are grammatically different parts of speech. 'British' is an adjective only. You can say 'He is a British man' or 'He is British', but you cannot say 'He is a British'. This is not possible grammatically. 'Briton' is a noun. It is possible to say 'He is a Briton' or 'They are Britons', meaning that they are people of British nationality. In fact, the noun 'Briton' is rarely used, and is almost never used in daily conversation. You mainly see it in journalism, for example 'Three Britons have been arrested in Bangkok'. Also, be careful not to confuse 'Briton' (referring to a person) with 'Britain' (short for Great Britain), which is the name of the country. The two words are pronounced the same.

its how it sounds rolling off the tounge same place

'Briton' is a noun referring to someone who is British e.g. "A Briton" = "A British person".