If your mac only shows a part of the photos on the SD card, you need to check the file system of your SD card in Disk Utility first. The reason why you can see all the photos on Windows but on Mac is that Mac checks the file system more strictly than Windows. So, if your file system has been a little damaged, it doesn't matter for Windows. On the contrary, on Mac, you usually find such a problem that the data you need is not displayed completely.
You can use First Aid in Disk Utility to check and repair your SD card before you take other operations.
- Open Disk Utility.
- Select the SD card at the left sidebar.
- Choose First Aid and click "Run".
- Wait until it finishes. (Don't do other operations when First Aid is running.)
If Disk Utility reports the operation has been repaired, you can use the SD card normally. But if it shows errors, you can try to format your SD card.
- Open Disk Utility.
- Select the SD card and click "Erase" on the top menu.
- Input a new name and choose a file system for your SD card.
- Click "Erase".
You need to pay attention to that after you format your SD card, you will lose all your data on it. So, you can back up your data on Windows before you start formatting. If you don't, you can use professional data recovery software like iBoysoft Data Recovery for Mac to recover your data after formatting.