Ribbon Controls and Their Formatting in mfc

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MFC

I am new in MFC Ribbon,
1. what is difference between button, gallery button and group(looks same like button) in mfc ribbon toolbar and when we use which control please explain.
2.my next problem is related with ribbon control alignment. i pick two combo box with different caption they both are not alined because of different no. of letters in caption and if i want to place two combo in one panel side by side how can do it with out using separator?

Example :-

Primary Property |_____________|
Secondary Property |_____________|

how to align above both ribbon control and how to place both control in one panel side by side with out using separator.