Difference between "How do you mean?" and "What do you mean"?

Hi,

How would you explain the difference between “How do you mean?” and “What do you mean”? I think when you ask “How do you mean?” you want somebody to clarify a certain point whereas “What do you mean?” is used when you don’t understand what somebody is talking about. Would you agree?

Thanks,
Torsten[YSaerTTEW443543]

TOEIC listening, photographs: Visiting the ruins[YSaerTTEW443543]

Hi Torsten,

I agree about ‘what’ but ‘How do you mean?’ suggests to me that you are asking ‘In what way?’. An example would be asking a question when someone has suggested that it would be a good idea to for example increase efficiency in a particular procedure.

Alan