There used to be three "streams" for Ontario secondary schools:
Academic - these were kids that teachers expected would go to universities after high school (if you're from the US, universities in Canada are analogous to US colleges)
General - these were kids that teachers expected would go to colleges or trade schools after high school (if you're from the US, colleges in Canada are analogous to US trade schools or maybe lower-tier colleges)
Basic - these were kids that teachers expected to do menial jobs straight out of high school
Those descriptions may be harsh, but they were absolutely the unwritten-yet-widely-understood implications of being put in one of these streams. I understand that later on the Basic and General streams were merged into a single "Applied" stream, but that's the gist. The course focus in each stream was tuned toward those expectations. Academic kids were steered toward math and science, General kids toward shop classes, and Basic kids toward courses like Home Economics.
The stream system was basically the Pygmalion effect applied to a couple generations of Ontario students. Kids put in the Academic stream tended to succeed because educators expected them to succeed, and thus educators would be more likely to give those students the attention and resources required for success. Kids put in a lower stream tended not to succeed again because that's what educators expected, causing those educators not to apply the same focus or opportunities as they would on kids in the Academic stream. It was absolutely self-fulfilling prophecy type stuff. There was also a hugely problematic racial component to the system. For example black students were far less likely to be placed in the Academic stream. It is/was a truly awful system and its death is long overdue.
Full disclosure: I directly benefited from the system, because I was a white kid put in the Academic stream. At the time I thought it was normal, but in hindsight I can see how unfair that system was.
I never heard it called streaming at the time, but there were explicitly labeled academic and applied courses meant for 'university students' and the rest. After the first year when you get to pick your own classes most students were pretty heavily coerced in one direction or the other, I was pushed towards the applied coursed but took all the math and science classes out of interest and stubbornness. It went as well as you could expect but at the time it felt like we were given a choice and that it was up to the students if they wanted to 'work hard' and go to university or take the 'easy classes' so you could get good grades.
It's been years since I thought about it but looking back, that really is not a great system.
This is roughly how I remember it going down. I remember choosing to take the academic level courses hoping to go to university but was unable to afford university after I graduated with decent grades. There were times I regretted it because there was a significant difference in difficulty between the two streams but now I'm glad I took the harder courses even if I never went to university.
What is Streaming? Academic streaming describes the process of dividing students into differentiated groups based on their perceived academic ability and/or prior achievement.
What is De-streaming? De-streaming means that students will no longer be separated into Academic and Applied Streams. Students will take a combination of courses made up of De-streamed, Academic and Open level courses.