A sealant is a longer lasting protection than a wax.
You seal your good work after de tar, polish etc
To add depth and gloss to the paint then you apply wax.
Depending on how safe you wash your car a wax will last 3-6 months normally.
Sealant up to a year and more depending on the sealant.
If you give your car the right love and care it deserves you should only need to apply a sealant once a year after full de contamination of exterior.
1st month full de con and polish, Sealant, wax.
Weekly to forthnighly safe wash using a drying aid like chemical guys speed wipe to add small bit of protection.
Every four months give it a coat of wax to keep the paint protected.