StreetPilot i3 Color Codes

 

I have somewhat of a simple question. Some may view this as juvenile...however it has a mystery twist. Okay enough of that. What does those colors on my i3 represent. Some are orange and some are red. Does it represent what type of road I am traveling on? Please respond. I am a novice to all those colors.

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Garmin Nuvi 660, Garmin StreetPilot i3(Retired), Garmin Nuvi 200(Retired), 1(wifey)+ 1(myself)=2 Garmin Nuvi 1350 LMT, Nuvi 2455LMT

Map legend

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Garmin StreetPilot c530, Mapsource