If their system is anything like in Quebec (probably is), the three year is the same as a 4 year (or 4 is the same as 5 for engineers).

In Quebec there's a stage between secondary school, and post secondary which lasts 2-3 years.

In terms of years, it looks like this: Primary:1-6 Secondary:6-11 Pre-Post Secondary: 12-13 Post Secondary 14-17(14-18 for engineering/etc.)

In the end they are equivalent, however differently structured.