Is there really that big of a maturity difference between an 18 and 21 year old?

The guy I’m seeing right now is 21, when I first started talking to him I didn’t really think that much of it but when my mom and aunt found out they lectured me on being careful and asked me why he didn’t just talk to someone closer to his age?

I’d understand this reaction if I was dating a 25 year old or something? I also really don’t get weird vibes from them but I don't know because I’ve never really been in a relationship before
Is there really that big of a maturity difference between an 18 and 21 year old?
Is there really that big of a maturity difference between an 18 and 21 year old?
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