Base training is conducted by a TRE on the actual aircraft with no punters ie not public transport on. Its usually 6 circuits on your first type and is the end of your type rating after passing the LST in the sim. After you have done the circuit's some paper work is filled out and the TRTO issues a course completion cert which is what you actually send off to get the rating issued.
Once you have a rating the rules change depending on if its the same type ie from one Turboprop type to another then it comes down to 4 circuits. Some of the jet sims and changes of type can be whats called zero hour. Ie the first time you land the machine its with a load on board. An example of this is 757 differences to 767 (on a correctly certified sim of course)
Line training is done on the line with PAX/freight ie a normal commercial flight by a Line training captain. It is completly internal to the company.