That could indeed be the difference. Teams in the U.S. have, with
very few exceptions, names that are plural (countable). The idea
is that the Giants is a team composed of giants. Each man on the
team is a giant. The Raiders is team consisting of men, each of
whom is a raider. And so on.
Note the peculiarity though:
The Raiders is a team ...
The Raiders win every game they play.
(Always with
the whether treated as singular or plural)
Companies in the U.S., on the other hand, are treated as single legal entities.
IBM is doing well this year. GE is doing poorly. (Always without
the unless the company has named itself something that contains
the, e.g.,
The Addison Group)
CJ