Apple and Google differ in their ways to integrate account keywords. Here are the main differences as well as a few tips on how to choose them:
Apple App Store

• Use 100 characters, including commas;
• Keywords should be specific to each local AppStore, and should therefore be entirely localized and not just translated; to get better results
• Do not repeat the keywords (even twice) already present in the title and do not leave spaces;
Avoid articles;and use only single words and single forms, 
• Focus on the long tail: tailored keywords bring you higher ranking;
• Your game’s category is automatically a keyword, no need to add it to the list.

Google Play Store

• Include your main keywords (around 5 times in your description), while keeping it interesting and readable;
• Use phrases; they are as important as single words and single forms;
• Check competitors’ descriptions before writing yours;
• Google’s roots are in search: use AdWord’s keyword tool as well as the auto-response search suggestions in Google Play to assess your keywords’ popularity;
• It can be a good strategy to be opportunistic and include some trendy and/or seasonal keywords (Christmas, New Year, Halloween,Olympics, etc…).

Hope you find it useful as I found!!
Comments and feedbacks are awaited 🙂