The giant squash, having the pseudonym "giant pumpkins" for its orange phenotype. Also, Atlantic Giant was a pseudonym associated with the giant squash in 1986, and a 1997-present US trademark. The squash has had numerous pseudonyms associated with it over the centuries. It has gotten larger, from allegedly 200 pounds in the 1820s, 300 in 1860s, 400 in 1900, 500 in 1970s, and 1,000 pounds in 1995. 1,500 pounds were purported with the passage of another 10 years (2006), and a one-ton fruit was announced in 2012.
A giant pumpkin is any squash cultivar of either Cucurbita pepo, or C. maxima that has been bred to produce fruit weighing anywhere from 200 pounds to over one ton. Atlantic Giant is a pseudonym associated with the giant squash in 1986 (US PVP 8500204), and a 1997-present US trademark. The Atlantic Giant pseudonym is a name only, and it is restricted (only since 1997-present), it is not a restriction on the giant squash and has never been.
Not to be confused with Atlantic Giant is “Dill’s” Atlantic Giant, which is a permanent US legal pseudonym for the giant squash, when it produces squash that are approximately 175 pounds, golden orange, oblong, et cetera, according to US PVP 8500204. It is a form of the giant squash, but it is not restricted, except that the name must be used if selling it (was restricted 1986-2004). This is the only restriction on the giant squash. If the squash does not closely fit the description of Dill's Atlantic Giant, then it is not Dill's Atlantic Giant.