Adjacent to Tokyo Disneyland is the younger but larger sibling Tokyo DisneySea (at 71.22 hectares), which opened in 2001. The park capitalises on its setting by the bay with a maritime theme.

In Tokyo Disney Resort, Tokyo Disneyland is slightly larger than Tokyo DisneySea. Tokyo Disneyland spans approximately 126 acres (51 hectares), while Tokyo DisneySea covers about 122 acres (49 hectares). While the difference in acreage is marginal, the walkable space in DisneySea often feels more expansive because of its massive central waterway, the Mediterranean Harbor, and the towering Mount Prometheus volcano. In 2026, the perception of "size" has shifted further with the opening of Fantasy Springs at DisneySea, a massive expansion featuring lands dedicated to Frozen, Tangled, and Peter Pan. Despite this, Tokyo Disneyland remains the resort's "flagship" in terms of total land area and the number of traditional attractions. For a 2026 visitor, both parks are massive compared to Hong Kong Disneyland (68 acres) but are significantly smaller than the "king" of Disney parks, Disney's Animal Kingdom in Florida (500 acres).