can you please elaborate on the difference(s)?
The most obvious difference to note is the width of the iron. Scrub planes have much narrower irons than do fore planes. Subsequently the iron of a scrub has a greater camber and is a narrower plane all together.
In modern planes scrubs still lack a chip breaker - it's of no advantage for a scrub plane. However hat's not a conclusive detail, early planes were all single irons without a chip breaker.
The easiest way to look at this is as follows. A scrub plane is a particular type of plane designed for one job. A fore plane is a bench plane in all aspects other than being tuned with a heavy camber and open mouth.
Here's the real difference though - Scrubs are of of Germanic / Dutch origin.
Fore planes are French / English.
ie - two different cultures having different means for the same job.
I hate to do this, but I have to disagree with CS. That article was written some time ago and I may be interpreting what he is trying to convey. It sounds as though he is saying a scrub is for the edge of a board and hence that's it's intended use.
This may be the only reason Stanley produced it however it was used by a people with quite the intimate relationship with axes and hatchets - particularly broad hatchets. It's very doubtful if your neighborhood cabinet builder would lay aside the hatchet for the scrub plane even more so that he would use a tool not in existence in his culture to rough joint the face of a board.
The Germans, French and English (an related) all used hatchets to size boards - even the face of the board as Moxon states.
Moxon writes more about the Fore Plane than any other plane, for his explanation accompanied by my commentary see: