Earlier quoted context omitted.
> these are distinct forms of street art Can you elaborate on this? I've always thought a mural was just a type of graffiti?
Graffiti is usually tagging [1], but includes other forms of (non-sanctioned) random acts of art and, especially, writing. Wall murals are usually sanctioned – either there is permission granted to paint a wall, or, often, they are commissioned. Usually there is only one artist or company that makes the "complete" mural, with much planning and coordination, and no intervention by casual passerby. In the source below,…
Certainly there are clear examples on both ends of the spectrum, but here's some closer to the boundaries of your definition from my own hometown - I wonder how you'd classify these:
1. This street of sanctioned individual pieces, mostly "tags" but elaborate full-wall pieces each by an individual tagger: https://maps.app.goo.gl/byceFqUQSaTeun2q6?g_st=ic
2. This unsanctioned (currently in court) full-building mural done by an ad agency: https://i.pinimg.com/originals/73/60/f6/7360f64042a71f241fe8...
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(personally I'd call the sanctioned tags both murals and graffiti, and definitely classify them as art, but I'd only call the ad agency piece a mural; neither graffiti nor art - though I fully acknowledge that last judgement is a subjective one and not something universal)