Short answer: in Canada, "unlimited data" means a fixed high-speed allotment, then unlimited data at a reduced speed for the rest of the cycle. The number to compare between plans is the high-speed allotment, not the word unlimited. Nothing cuts off and nothing bills overage; it slows down.
Every newcomer comparison eventually hits the same confusion: two plans both say unlimited, one costs twice the other. The difference is the high-speed cap, and once you know to look for it, plan shopping takes five minutes.
How the mechanics work
A Canadian plan advertises a bucket of high-speed data, 20, 50, 95 or 100 GB. Use it up and the connection continues at a reduced speed until your cycle renews. Reduced speed handles messaging, maps and email; it struggles with video calls and streaming. So the practical question is how much high-speed data your month actually uses.
How much you actually need
Messaging, maps, banking and browsing run 5 to 10 GB a month. Add social video and music streaming and most people land between 15 and 30 GB. Hotspotting a laptop is the multiplier: video calls from a tethered laptop can burn 1 GB an hour, which is why heavy hotspot users take the 95 or 100 GB tier and everyone else does not need to.
Matching the tiers
Staying under 90 days: prepaid at $25 to $75 CAD covers 20 to 95 GB of high-speed data with the unlimited reduced-speed tail. Staying longer: postpaid at $30 for 50 GB (Fido) or $40 for 100 GB with hotspot included (Rogers), no contract, and ordering before arrival waives the $80 setup fee. The plans page lays the tiers side by side, and the arrival-date finder picks by your stay length.
Common questions
Does reduced speed cost extra?
No. That is the actual meaning of unlimited here: no overage bills, ever. The trade is speed, not money.
Is tethering included?
It varies by plan tier, which is exactly the kind of line-item to check before buying. The Rogers 100 GB tier includes hotspot; the Fido 50 GB tier does not.
Prepaid or postpaid for data?
The data mechanics are identical. The difference is the credit check, the contract terms and whether payments build Canadian credit history; the prepaid versus postpaid guide covers that decision.