The second variant is more a less a the same as the RGB triples but instead of an array the RGB triple is specified as a string with the hexadecimal RGB values. This is commonly known as the "HTML color specification" since this form often used when creating WEB pages (for example in CSS sheets).
For example:
SetColor('#333')
, note that this is a short form for
SetColor('#333333')
SetColor('#12be7a')
SetFillColor('#99eff5')