You may be an English teacher, but clearly not a linguist!
I am a linguist, and I can tell you: you are correct, correct, and incorrect.
It's not a punctuation difference... correct.
It's a linguistic (or linguistical, if you're a brit) difference.... correct.
But ALL differences to do with language are LINGUISTIC, whether its orthography (punctuation), syntactic, morphological, lexical, or what have you.
So even if it WAS a punctuation difference, it would still be a linguistic difference, so..... (incorrect).
In this case, it is a morphological/lexical/grammatical difference.
Morphological difference:
Your (possessive pronoun - one morpheme) vs. you're (contraction of 'you are' - two morphemes, second one being a conjugation of the verb (to be)).
Lexical difference:
Your = possessive pronoun (2nd person singular) - indicates the object is possessed by the person represented by the pronoun
vs. you're = pronoun (2nd person singular) + verb (to be) - indicates that the person represented by the pronoun is (something).
Grammar difference:
The former is a word, and the latter is a phrase.
For my money, the better slogan would have been :
"Grammar matters" because this is essentially a grammatical difference not a punctuation (orthographic) one.
You may be an English teacher, but clearly not a linguist!
I am a linguist, and I can tell you: you are correct, correct, and incorrect.
It's not a punctuation difference... correct.
It's a linguistic (or linguistical, if you're a brit) difference.... correct.
But ALL differences to do with language are LINGUISTIC, whether its orthography (punctuation), syntactic, morphological, lexical, or what have you.
So even if it WAS a punctuation difference, it would still be a linguistic difference, so..... (incorrect).
In this case, it is a morphological/lexical/grammatical difference.
Morphological difference:
Your (possessive pronoun - one morpheme) vs. you're (contraction of 'you are' - two morphemes.
Lexical difference:
Your = possessive pronoun (2nd person singular) - indicates the object is possessed by the person represented by the pronoun
vs. you're = pronoun (2nd person singular) + verb (to be) - indicates that the person represented by the pronoun is (something).
Grammar difference:
The former is a word, and the latter is a phrase.
For my money, the better slogan would have been :
"Grammar matters" because this is essentially a grammatical difference not a punctuation (orthographic) one.