First, spaghetti is already plural (I think if there were a word for a single strand it would have to be a spaghetto, but there isn't) so don't add an "s" to it.
Spaghetti is one type (out of hundreds of varieties) of pasta.
Pasta can be either fresh or dry. Fresh is still flexible, having been made recently for use soon, whereas dry was made some time ago, dried and packaged for use far into the future.
One often refers to "fresh pasta" but I've never heard of fresh spaghetti, or fresh penne, or fresh anything except the general term, pasta.
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