I am running OS X El Capitan on my late 2009 iMac. I've got iCloud turned on.
When in Safari on my iMac I can access the Safari tabs on my (old!) iPad, but not my iPhone 7 Plus.
My iPhone accesses Safari tabs from both the iMac and the iPad.
My iPad accesses Safari tabs from the iMac but not the iPhone.
When in Safari on my iMac I can access the Safari tabs on my (old!) iPad, but not my iPhone 7 Plus.
My iPhone accesses Safari tabs from both the iMac and the iPad.
My iPad accesses Safari tabs from the iMac but not the iPhone.