The side streets around my house. Some are gray and some are a thick orange why is this? All are small side streets. Do they offer a college course for this damn head unit?????

although side streets some may be main side streets so they are thicker orange i think is main road blue is highway thing grey is regular side road

that would be my assumption

I was driving around while looking at the nav and the roads I passed by the other day...

It appears that the grey roads are small side streets, or neighborhood streets, a good portion of which are small enough that they don't even have lane paint on them.

And the orange ones (or is it yellow?) appear to be higher traffic roads, numbered routes, multiple lane roads, etc.

And the blue ones are freeway/interstate type roads with on/off ramps.

In short: Grey > Orange > Blue in order of traffic volume, lowest to highest.