Lately, I (for lack of a better word) noticed something that got me confused help If anyone could help me, I would be grateful.

First of all, two examples:

a) "I don't know what's going on," Clark said.

b) "I don't know what's going on," said Clark.

Secondly, please bear with my shower of questions:

1) Is there a difference between the meaning of the two, or can they be used interchangeably? (It seems to me that b) is putting a bit of emphasis on who spoke, but it might be just me.)

2) Is it a UK/US thing? I think I've only seen b) used in UK writing, but I could be entirely wrong.

3) Using both structures in a story would be considered as 'variety' or as 'inconsistency'?

Thanks a lot!!
AnnaBtG.

What we've got here is failure to communicate...