The ones that do not hire from the start are the ones that try to sell you their package by telling you that you will get


-Great QOL
-Fast upgrade
-Great benfits

etc etc

anybody can be fired at any time but if you are hired from the start you have more rights even on probation that if you are a student in training that is not employed. Dont let anybody fool you with something different

If there is no difference then ask them why they do not hire you from the start.