I'm not sure exactly what you're meaning here. Every device, iPhone, iPad, or Mac, maintains it's own local Photos Library. And iCloud, too, has its own Photos Library for your account. When you engage iCloud Photos on a device, then the Library on that device is kept just the same as the iCloud Photos Library. So, for instance, if you take a picture with your iPhone, it is added to the iPhone's Photos Library, copied to iCloud Photos Library, and then copied to the Photos Library on each of the other devices. If you delete a picture on your Mac, then that picture is deleted at iCloud and on all the other devices. iCloud Photos is a synchronization service; it keeps every Library exactly the same.
So the iPhone doesn't send pictures to the Mac, or vice-versa; iCloud.com is the center of all the synchronization.
To synchronize an iPhone with iCloud.com, you need to turn on iCloud Photos at Settings>Apple ID>iCloud>Photos. To synchronize a Mac with iCloud.com, you go to Photos' Settings>iCloud. Also, since Macs can hove more than one Library, you need to make sure that your Photos Library is the System Library by going to Photos' Settings>General,
Here, "Use as Photos System Library" is grayed out, because it already is.
You will also need to decide if you need to save storage space by using Optimize Storage. You can use "Optimize Storage" on the Mac, on your iPhone, or on your iPad. You can set this on any device, independent of the others. If you want, you set this in the Photos Settings on each device. If you set a device to "Optimize Storage," then Photos may store only smaller images on the device and rely on iCloud to keep the full sized images. So, if Optimize is chosen, and you want to magnify a picture to see more detail, Photos will reach out to iCloud to get a full sized image for you to zoom in on. It's the same for editing or printing or anything that demands the full picture. Your optimized Library may take up less than 20% of the space of a fully downloaded Library. I use Optimize on my iPhone, but I don't need to on my Mac, which has way more storage available, I know that Optimize Storage makes it more difficult to back up the Library.
I haven't mentioned anything about Calendars and stuff-- they're not part of Photos.
Does this help?
