Merging/Importing iPhoto/Photos library into Another Photos Library: PowerPhotos vs Photos.
If you have a lot of organizational effort in your Aperture library you might want to use the paid version of PowerPhotos to merge the Aperture library into your current Photos library.
I ran a number of tests with a 3119 photo, 72 video and 97 keyword Photos library with keywords, captions, keywords and locations. I merged it into an empty library using Photos and PowerPhotos. This is what I found was imported by each;
PowerPhotos: Photos:
Albums*** ----- N/A ------
Smart Albums (as regular albums)** ----- N/A ------
Captions Captions
Titles Titles
Keywords* Keywords (some but not all-see Note *)
Original images Original images
Edited images Edited images
Loctions Locations
Favorites Favorites
Can detect and exclude Duplicates
duplicates upon import or not
Neither method could import/merge projects.
Both methods could import older iPhoto libraries into a Photos library when the iPhoto library couldn't be migrated into a Photos library.
NOTES:
*The Photos app only imported 84 keywords out of 97. PowerPhotos merged 147 keywords, some which apparently were in the images but not read by Photos at the time of import or keywords delete along with photos but not purged from the database.
**The original library had 90 Smart Albums. All were merged by PowerPhotos but, as indicated above, the Smart albums were brought over as regular albums. No album of any kind were imported by Photos.
***The original library had 34 regular albums and 1 folder with some nested albums. PowerPhotos merger all of them successfully.
The original library had 72 videos. Photos imported only 57. PowerPhoto got all 72 in its merge.