Title says it all. What's the difference between just stacking FX on a track in the FX bin, vs an FX chain?
when I'm just stacking FX on a track, does the order I applied them in matter?

The order they're applied in matters in both cases, yes.

The main difference between an FX chain and stacking them in the FX bin is you can recall the chain all in one go "en masse", whereas the stack has to be built from scratch every time.

For me the second main difference is that you loose ACT once the effect is in FX chain...

ACT should work even in fxchains as long as the plugin UI is open and has focus.

As mentioned above the effects in the chain are treated as a unit which can be saved and recalled. FX Chain is also the wrapper used for standard plug-ins in the ProChannel. FX Chain provides more automation options such as an additional gain control before and after the effects and the ability to automate multiple controls on the effects in the chain with a single envelop.

I find it quickens my workflow. When I'm songwriting or just playing with melodies, I usually have a certain set of plugins that I use because I know them well and can work with them quickly. By putting them in an effects chain it's just a single click and drag from the browser and they are set up ready to go.

Noel, act does not work properly on FX chain nobs and buttons in my experience. For this reason, I often can't put th2 in the pro channel.

So when using an FX chain, which you can re-use on several tracks, does it use the same plug-ins, ie, they become common to all tracks where you use them like a bus therefore saving CPU or does it use a separate instance?
 
Thanks.

Noel Borthwick [Cakewalk]
ACT should work even in fxchains as long as the plugin UI is open and has focus.

There was a discussion about that, but I can not find it. If that was not you, someone else has explained there why it does not work (on purpose).