You will be able to display your JPEG images on either of the players (via either disc, a usb thumb-drive, or wirelessly file sharing) you are considering to purchase. Likewise, playing video from your iPhone thru either of these players is not possible. Both of these machine's capabilities are nearly identical as are their respective retail price(s). Even aesthetically speaking they look very much alike.
Realistically, brand recognition & loyalty are very often the biggest deciding factor as many options and functionalities are comparable with so many electronic products in this day and age. That being said neither of these options are bad ones and either will provide relatively the same enjoyment experience.
Additionally a great option for playing content from your iPhone (or iCloud), if this is something you would really like to do, would be to also install an Apple TV (ATV). For streaming options most of my clients are absolutely thrilled with the ATV. I have experienced very few issues with this product and it seems to be simple enough even for my most technology challenged clients.
Hopefully this has been informative for you and will somehow help you with your decision making process.
For more extensive information and specs visit the links listed below: