Difference between GGA and RMC sentences in NMEA

Question

I need Long/Lat and also angle of a vehicle to the North at the same time. I found I can use GGA message to extract Lon/Lat with no problem. However it doesn't give me the angle that I need.

Then I found RMC message and seems to be what I'm looking for. The problem is I'm not sure if the Lon/Lat in both messages are the same? also if 'Track angle in degrees (True)' is the angle to the North?

Thank you in advance for sharing your experience or ideas.

For your observation:

RMC message:

https://www.trimble.com/OEM_ReceiverHelp/V4.44/en/NMEA-0183messages_RMC.html

enter image description here

Answer 1

Track angle (field 6 in RMC) is the direction the vehicle is moving, not necessarily the direction it faces, although for a ground (wheeled or tracked) vehicle these are very likely the same.

Yes, it's relative to true north.

Testing whether two pairs of Lat/Lon coordinates are equal or not is a rather trivial thing.