If you enable iCloud Photos on your iPhone and on your Mac, then assuming that you have enough iCloud storage space, they will synchronize their photo libraries through iCloud.
Photos taken on one will show up on the other. Photos deleted on one will show up on the other. (A Mac can have several Photos libraries, so could have a main one that synchronizes with iCloud, and others that are strictly local.)
Set up iCloud Photos on all your devices - Apple Support
Whether or not you enable iCloud Photos on your Mac, you can log into the iCloud Web site to see photos and other data that is being synchronized to iCloud. It is just that the options to have the Photos, Calendars, Contacts, etc. applications synchronize data might be a little bit more convenient.