Blaithin: This is the most common spelling and is believed to mean "little flower" or "small flower". It's derived from the Irish words "bláth" (meaning "flower") and "ín" (meaning "small" or "little").
Blaithín: This spelling is slightly less common but has the same meaning as "Blaithin" - "little flower". It's a more traditional spelling.
Therefore, both "Blaithin" and "Blaithín" share the same meaning, which is "little flower".