It seems to me that abrasive saw is a term mainly used in the US (the Wikipedia article on it has no links to pages in any other languages), whereas angle grinder has some 20+ translations. So, can someone clarify whether discs for abrasive saws are interchangeable with (thin/cutting) discs for angle grinders and what other differences there might be between these two tools (even if just in the US)?
Generally an abrasive saw is a bench-top tool. It looks like a miter saw but has a grinding disc instead of a toothed blade. The dist will be on the order of 12-16 inches in diameter for a typical saw. Angle grinders are handheld tools with much smaller discs - usually between 4 and 8 inches in diameter. While there are come very large angle grinders and some very small abrasive saws, usually the wheels will be different.
For each, a range of wheels are available. All abrasive saw wheels are designed for cutting on only the outside edge, and will be thick enough to support them selves over their diameter. They will be made of slightly different abrasives, optimized for the metal that you are cutting.
Some wheels for angle grinders are designed to cut along the outside edge as well. These are usually called 'cutting wheels' or 'cutoff wheels.' Because of the smaller diameter, they can bu much thinner than abrasive saw wheels without shattering too easily. Being thin allows them to cut faster, reduces waste from kerfs, and makes them lighter. For angle grinders, other kinds of blades are also available for surface grinding. These wheels are meant to cut on one flat face for blending welds, cleaning metal, contouring, and other surface work. These wheels will be thicker so that they can handle the loads applied. There are a bunch of other types of wheels from flap discs and soft pad grinders to wire wheels for other specific purposes.
So in general, event though they might sometimes be the same diameter in a few cases, discs for abrasive saws and cutoff grinders will not be interchangeable. In any case, be sure to check that the rated rotational speed (RPM) for the abrasive blade matches or exceeds the spindle speed of your tool.
In general they are not interchangable. But if they use the same speed and clamping method then they might be. Best to check with the manufacturer. Some discs are meant to be used only on the outside edge for cutting, whereas others might be used side on (say, 35 degrees) to grind. We have problems in the UK of untrained people using cutting blades for grinding and having the blade shatter.