The photo above shows a Frontage road in Nevada off of Interstate 80 providing access to a truck stop and a few other locations.
Feeder, frontage, access, outer, and service roads. What’s the difference? Not much in the USA. These roads run parallel to major highways and provide direct access to various locations off the highways. You might be able to figure out where a person is from by their choice of word for these roads.
One of these could be used a bit more technically by some, but many times is just meant as general access. Service roads provide access to locations not for public access but instead for work and servicing crews. Example linemen, power stations, telephone, windmills, railroad, and other similar functions. Some may just call these private roads as well.
If something new comes to light about these roads this post will be updated.