As the paint dries the paint becomes transparent. This taints the way one sees the color. When in the liquid state, colors in acrylic paint appear to be lighter than they will be when dry. One must account for this discrepancy by visualizing how the color will appear in advance. Beginning acrylic painters should expect some trial and error as they learn how to do this.
Acrylic paint tends to be less glossy than oil.
To create glazes or increase gloss one must use gel medium. Gel medium is essentially clear polymer binder that, when mixed with the paint, slows drying, creates transparency, and adds gloss to the acrylics. Some high solid gels can even give an impasto surface to the paint. There is an extensive variety of products now available for the acrylic painter to aid in the manipulation of the paint's character. By adding water to acrylics they can be thinned to have a more liquid consistency.