Graduated licensing rules depend on the province. In AB the only differences between a GDL license and a full license are that you are not allowed any alcohol, you lose your license at half the demerit points of a full one and you can not upgrade to a taxi, truck or bus license.
A foreigner that can not prove that they had a license before would in AB be subject to the same rules as a person who never had a license, that is, they would need to start by taking the written test, get a learners permit and then need to wait a year until they get to take the road test for a GDL license. On a learners permit, you may only drive with another adult who has a full license and I believe you may also not drive at night. Having passed the road test, they would get the GDL license and then would need to wait two years before taking an advanced road test to get a full license.
If they can prove that they had a license but not how long, they would be allowed to take the GDL road test right away instead of waiting a year. If they could prove that they had their license for a while, they would be allowed to take the advanced road test right away and get a full license.
If they come from a country that has an exchange agreement with the province, then of course they don't have to take any test, they just exchange their license for a Canadian one.