Despite the fact that FLAC and ALAC have very similar names and principles, they came from different platforms. FLAC is distributed on Windows and Linux, while ALAC was developed by Apple for iOS and MacOS systems. Both codecs use lossless compression and ensure high sound quality. In recent years, the popularity of the FLAC format has increased significantly and technically, FLAC bypassed its rival in all aspects. In music retailing, FLAC is fairly common, and ALAC is almost unheard of. Even Apple does not sell songs in ALAC format.
After 2011, Apple stopped further development of the ALAC and added support for FLAC in iOS 11. It would seem you can forget ALAC, FLAC is just a more widely accepted format with that alone making it better. Unfortunately, iTunes still does not support FLAC, and users have to choose which format to use to store music.
Thankfully, if you have the right tool then it's possible and easy to get your lossless FLAC albums and songs into iTunes or vice versa. Here I would recommend Audio Converter Plus to you. It allows you to convert almost all popular formats including WAV, WMA, OGG, FLAC, AAC, WAV, etc. It is really easy-to-use with a few steps. Here's a guide mainly focused on introducing how to convert FLAC music to Apple Lossless (.m4a) for importing into iTunes, so that you can play them on iTunes itself or put onto your iPhone, iPad or iPod for portable listening.
1 Install & Launch the Converter
Download Audio Converter Plus and install on your computer following the instructions. Then, launch it.
2 Add FLAC Files
You can do that by dragging and dropping the source from the Windows explorer directly onto the center pane of the program, or by going to "Add File" button located the upper-left toolbar to browse and select the FLAC files. You can also select the whole folder by clicking "Add Folder" button on toolbar.
3 Choose Output Format
Select "ALAC - Apple Lossless Audio" from dropdown menu and click the "Encoder options" button. Since we do not want to lose quality on resampling, we should leave all the compression parameters as the original.
4 Select Destination Folder
You can select a folder to save the converted files by clicking "Browse", or skip this step and the files will be saved by default. We also recommend choosing the option "Keep the original directory structure".