If used as a preposition, they are both used in the same way. However, only 'except' can be used as a conjunction, not 'except for. See https://dictionary.cambridge.org/grammar/british-grammar/except-or-except-for

Hey Annie. L, how are you? Firstly, you should know that you use the word ''except'' to introduce the only thing, person, or group that your main statement does not apply to. 1) When used with a noun phrase: You usually use ''except'' in front of a noun phrase. E.g.: ''Anything, except water, is likely to block a sink.'' E.g.: ''All the boys except Peter started to laugh.'' --> You can use ''except'' in front of object pronouns such as ''me'', ''him'', or ''her'', or in front of reflexive pronouns such as ''himself'' or ''herself''. E.g.: ''There's nobody except me.'' E.g.: ''John didn't trust anyone except himself.'' *NOTICE: You should not use ''except'' in front of subject pronouns. Don't say, for example, 'There's nobody here except I'. 2) When used with a verb: You can use ''except'' in front of a to-infinitive verb. E.g.: ''I never wanted anything except to be an actor.'' E.g.: ''She seldom goes out except to go to church.'' --> After the verb ''do'', you can use ''except'' in front of an infinitive without ''to''. E.g.: ''There was little I could do except wait.'' 3) When used with a finite clause: You can use ''except'' in front of a finite clause, but only when the clause is introduced by ''when'', ''while'', ''where'', ''what'', or ''that''. E.g.: ''I knew nothing about Sarah except what her dad told me.'' E.g.: ''I can't remember what we ate, except that it was delicious.'' *NOTICE: You should not use ''except'' immediately in front of a finite verb. Don't say, for example 'I can't remember what we ate, except it was delicious'. 4) ''Except for'': You use ''except'' for in front of a noun phrase when you are mentioning something that prevents a statement from being completely true. E.g.: ''The classroom was silent, except for the sound of pens on paper.'' E.g.: ''The room was very cold and, except for Paul, entirely empty.'' Hope that helps!!!