Ipa format is the official default installation package of itunes. Double-click it directly to identify the installation on itunes, and then connect Iphone for synchronization. The Pxl format is the installation package of 9 1 mobile assistant. I heard that this assistant has certain risks. Personally, I suggest using itunes for installation and synchronization as much as possible. That is to say, try to choose ipa format when installing software. However, the pxl format can be converted into ipa format, and there are tutorials online, which is quite simple. So don't mind the format when downloading.