You'll never see the International style dancers breaking hold or contact, even briefly. Some with less ability may accidentally lose body contact here or there, but it's never on purpose for the sake of executing something in open position such as an underarm turn; Such things are not allowed. The exception is showdance, where all is allowed including lifts.
Still, even in showdance division, you will see a difference between American and International style dancers. Both are rooted in the same fundamental technique, but American style tends to showcase open work to a much greater extent. The current trend in American style is perhaps 10 to 15% closed work, usually for no more than a bar or two at a time. And even then, many dancers will opt for non-traditional holds. One of the key defining characteristics of modern American smooth is "connections", i.e. weaving and transitioning between various positions and holds. To stay in closed hold for extended periods of time, while not against the rules, is not typical of the style. One would begin to wonder why the couple isn't entered in the Int'l style division instead.
By contrast, when Int'l couples do showdance, they do tend to spend a lot of time in closed hold with contact. It's more typical to dance long closed groups, saving the open work for intros, endings, and the occasional interlude. The connections to and from closed position are not usually as slick, but the closed work itself is far more interesting and technically demanding.
If you're watching a competition in America such as the Ohio Star Ball, these differences may be somewhat less apparent since our crop of Int'l dancers may be influenced by their American style colleagues. But the differences will certainly be enough to notice at any rate.
As an aside, I mostly agree with Terence about dabbling in other styles primarily for the purpose of boosting earning capacity. American smooth dancers, however, may be the exception to this. Our style draws heavily on skills acquired by dancing other styles. Any American style dancer who doesn't have a solid background in Standard will not make it very far in the competition circuit. So for us, learning Standard is more of a requirement than a luxury. And with current trends the way they are, the same is true of Latin to some extent. Melissa and I were some of the better technical standard dancers in our group of smooth competitors. But our marks improved considerably when we switched to a Latin coach for a year.
Regards,
Jonathan Atkinson
www.ballroomdancers.com