It is very difficult to pick a melanoma from it’s appearance to the naked eye. One of these is a melanoma, the other is not.
Using the ABCDE tool each would be determined to be a melanoma.
(A = Asymmetric, B = Border is notched or irregular, C = more than 4 colours, D = Diameter over 5 mm, E = Evolving)
However it is more accurate to assess the skin with a dermatoscope which clearly shows that only one of these lesions is a melanoma, the other is a seborrhoec keratosis which is a benign age related lesion. A dermatoscope is essentially a skin microscope that requires skill and experience to use.