It is difficult to distinguish between blemishes and melasma. How can I tell?

Lately, I've noticed a lot of brown spots around my cheeks, so I thought I had developed blemishes, but people around me looked and said it could be melasma. Now that I've actually searched online, I realize there are so many different types of pigmentation—like freckles, blemishes, and melasma—that it's really hard for me to tell the difference on my own.

To me, there are areas that look like small brown spots, and others where several are clustered together to look like wide stains. In particular, since the pigmentation is similar on both cheeks, it is even more confusing whether it is just blemishes or melasma.

I've heard online that you can distinguish it to some extent by looking at the shape or location of the pigmentation, but I think there are limitations to judging solely from a photo. I am also wondering if it might actually be counterproductive if I were to receive laser treatment for melasma, mistaking it for a common blemish.

Has anyone ever thought they had blemishes at first, only to be diagnosed by a dermatologist as melasma or another type of pigmentation? What criteria were used for classification, what tests were performed at the dermatology clinic for verification, and whether the treatment method changed after the consultation I'm curious. I'd like to hear the experiences of those who, like me, found it difficult to distinguish on their own.