>>851253Interpretation are the people who walk people around the park telling them about different areas, history of the park, the wildlife, answer questions at the visitor center, etc. It can involve different things depending on the park, for example at the Everglades, there are interpretation rangers that take people on kayaking trips.
Natural Resources are the people who take care of and document the fish, wildlife, plants, archaeological sites, soil, geology, etc of the park. You could be trapping and tracking animals, doing habitat restoration, fighting invasive weeds, documenting arch sites, etc.
For trails, that is generally split between maintenance and natural resources I believe in smaller parks. Larger parks probably have dedicated trails rangers.
Also, depending on the park, there can also be specialized rangers. One of the parks I worked at had specialties for climbing rangers. Some other parks have guide rangers that do mountaineering and/or white water rafting trips, back country rangers who patrol the trails on foot or horseback, and search and rescue.
At smaller parks, many rangers get the chance to do a wide range of things. For instance, I climbed and was on the SAR team, did trail work, worked in fees during our busiest time of the year, caught and tracked bats, did some archaeology, and led a few interpretive walks, even though my main job was invasive weed control.
