I see differences like this many times on corporate bulleting boards - the Americans go for identikit, smiling, 'go-get-em' corproate-style images while the Europeans generally provide a family snapshot or passport photo.
Oddly enough, meet them in person at a business meeting and as a broad generalisation it is the opposite: the Americans are usually dressed and act more relaxed and matey while the Europeans are more likely to be in full suit and formal.