Hi Leslie, The two words can usually be used the same way when used as an adverb meaning "solely or exclusively": "I only see stars tonight" "I just see stars tonight" In these example the words "only " and "just" are modifying the verb "to see" When used as an adjective, you have to use "only" "I am the only person outside today" You can't say: "I am the just person outside today" Although you can rephrase this to use an adverb again, modifying the verb "to be": "It's just me outside today" "It's only me outside today" However, "just" can have other meaning that "only" can't. These two sentences can mean the same or different thing based on context "I just bumped into you" "I only bumped into you" Both can mean that you bumped into me and didn't do anything else. But the first one can mean that you bumped into me, but it isn't a big deal and I shouldn't be mad. In this case "just" means "merely". (only can be used this way too, but "just" is more common) These two sentences can mean the same or different thing based on context "I have just enough money to buy this watch" "I have only enough money to buy this watch" Both can mean you have enough money for the watch and nothing else. However the first sentence can also mean you "barely" have enough money for the watch. Another example of this usage would be "I just missed the bus!" These two sentences can mean the same or different thing based on context "I just painted the fence" "I only painted this fence" Both can mean that you painted the one fence and no other fences. However the first sentence can also mean that you painted the fence very recently. In conclusion, they can be used in the same way when used to mean "solely or exclusively" (depending on sentence structure), but "just" has some extra meanings in some contexts.

Just is motion of speech or only is number.