If you still have the visa approval letter you received with your visa, it should tell you which route you are on.
The 5-year route is the standard route and is issued to applicants who meet all the spousal visa requirements... the majority of people will be on the 5-year route.
The 10-year route is an exceptional circumstances visa, which is granted outside the immigration rules when the applicant does not meet the financial requirement for a spousal visa, but is deemed to qualify to live in the UK under Article 8: Right to Family Life. It is usually only granted when the applicant has a UK citizen child living in the UK whose life would be severely disrupted if the visa was to be refused, meaning they would either have to be separated from their parent, or would have to leave the UK and move to another country in order to be with their parent.
If you are on the 10-year route, you should be well aware of this fact, as you would have been given special permission to be allowed into the UK on the 10-year route instead of your visa being outright refused because you didn't meet the requirements.
