Upland Blvd. is a prime example of a tertiary road in which it is not a high-capacity arterial like Alta but it sees more traffic than a typical residential street. It is wider and and has lane markings, which are often signs that a street serves as a collector road. Compare that to Evergreen Ave, which is narrow, lacks lane markings, and has many speed bumps to discourage higher-speed through traffic (though some tertiary roads will have speed bumps here and there). This is an indication that Evergreen is intended to be a local neighborhood street that consequentially sees more through traffic due to it making a beeline through multiple neighborhoods and major streets.

Additional context can be found here: https://wiki.openstreetmap.org/wiki/Tag:highway%3Dtertiary