USB 3.0 = Blue ports. The Red ones denote "High Power". The green ones, I have no idea. Maybe Always On, like the yellow ones.  USB 2.0 ports can be all sorts of colors but the majority of them are black or grey.

A blue port/ USB 3.0  is much faster.  USB 3.0 ports don't have to be blue, however. They may be marked as "SS" (Superspeed) instead.

USB 3.0 has transmission speeds of up to 5 Gbit/s, which is ten times faster than USB 2.0 (480 Mbit/s) before taking into account that USB 3.0 is full duplex whereas USB 2.0 is half duplex, giving USB 3.0 the potential total bandwidth if utilized both ways to twenty times that of USB 2.0.

http://www.asprangers.com/post/2012/10/02/What%E2%80%99s-in-color-Yellow-Blue-Gray-color-USB-Ports-on-Lenovo.aspx

Red or Yellow USB connector - Sleep and Charge

Red Type A USB Sleep and Charge plug

This is not a USB specification, but more of a feature. This color indicates that the connector does not power off during sleep or standby mode. On laptop or desktop computers they are great for charging external devices like smartphones. Its specification can be any of the above, so check your computer or device documentation for the exact one.

http://www.geeksinphoenix.com/blog/post/2014/01/12/How-to-tell-what-type-of-USB-connector-you-have-by-color.aspx