Hello annefromannandale,
Thanks for reaching out in Apple Support Communities. We understand that you would like to know what is the difference between the two Share My Location options in Privacy Settings. We're happy to help. The first Share My Location is to share your location with friends and family. "When Share My Location is turned on, you can share your location with friends, family, and contacts from your iPhone, iPad, or iPod touch with Find My. You can also share your location in the Find People app on watchOS 6 or later with Apple Watch models that have GPS and cellular and are paired with your iPhone." The second Share My Location is essentially very similar. "Share My Location: You can choose to share your current location with others, on a temporary or ongoing basis, from within certain apps such as Messages and Find My."
Check out the following support article:
Find friends and share your location with Find My
Location Services & Privacy
About privacy and Location Services in iOS and iPadOS
Cheers!