36A and 34B — they're both technically a B cup. They're called Sister Sizes (similar, but not the same!). Here's a quick…

Bra Sister Sizes Why Different Bra Sizes Fit the Same Woman

Understanding Bra Sister Sizes

How does a size 32A bra and a 32B bra differ? - Quora

Understanding Bra Sister Sizes

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Bra fittings: 6 things you didn't know about them - Chatelaine

Sister Sizing is an alternate bra size. Simular but not the same. 32c ,34b , 36a are Sister sizes.

Bra size - Wikipedia

Bra Fit Tips and Tricks-How to Tell if You're Wearing the Right Bra