Technically it IS Magus vs. Guile. Magil/Gil is just Magus later (who knows how much later?). Guile/Alf is just some random mage character.
Guile has likely been retconned to be Magus though, whereas Magil has been retconned out of the canon storyline.
I go by what's official though, not supposedly maybe could be how it is. To me, Guile has yet to be proven to be Magus, while it HAS been proven that he is not. I don't think anyone
can be retconned out of the 'canon' story of the Chrono series since each new story starts in a new timeline or dimension...That's just how the series works.
In the beginning, 1st playthrough, Magus is going to have a higher starting Magic stat than the rest of your crew so that Dark Matter is going to be more powerful than Luminaire, Flare or Shock. He also has access to all 4 Magics. He also has a decent attack & critical (both of which are made better in CTDS). Double & Triple Techs are overrated, but Magus has the best all-targeting Magic Triple Tech with Omega Flare, anyways...I think by not having learned Double & Triple Techs, Magus is basically telling everyone how pointless they are. Why waste waiting for two turns to come together for what you can do better with two turns separately?
I think Magus
does change a bit by basically
asking Crono & Co. (though at the time it was just the Co.) to let him join them. It's one of his greatest moments of weakness in the game besides when the party enters the distortion created by the Time Egg and he sees himself & Schala...He isn't above working with others, but he prefers to be in control...Which makes sense because his ultimate goal is revenge against the one who took that away from him almost completely...
For more in-depth (and
slightly less off-topicness), there's always 23 pages & over 300 posts of people saying
Why Magus Is So Cool...