I've used the Play Store to look for apps and according to the developer's description, those two apps have the same meaning, but run on different devices:
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Clean Master x86 is developed exclusively for devices that are running on Intel CPUs. It won't install or run on normal Android phones with Snapdragon CPUs, for example.
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Clean Master Lite is developed to be installed on phones with less than 1 GB of memory. The software is using modules that are low on memory while keeping performance an cleaning the phone accurately.