Basically you've been issued a visa that allows you to enter Qatar to take up employment.

After you arrive your employer has three months in which to complete the formalities to get you a work/residence permit.

A work visit visa is essentially a business visa for people who have work to do but don't intend to settle in the country.

Residence permits are usually issued to non-employable residents such as minors with their family etc.

However all these are interchangeable.

The bottom line is what matters is getting into the country and going through the procedures for a residence/work permit. These include the obligatory medical and police registration. All are handled by the sponsor/employer.