That excerpt seemingly implies that a Commonwealth territory is not an unincorporated territory. Perhaps, "than that of other US ... territories" would have been more clear.
I think one can be more specific regarding the guidelines.
Organizational Term: Definition
insular area: A jurisdiction that is neither a part of one of the several States nor a Federal district. This is the current generic term to refer to any commonwealth, freely associated state, possession or territory or Territory and from July 18, 1947, until October 1, 1994, the Trust Territory of the Pacific Islands. Unmodified, it may refer not only to a jurisdiction which is under United States sovereignty but also to one which is not, i.e., a freely associated state or, 1947-94, the Trust Territory of the Pacific Islands or one of the districts of the Trust Territory of the Pacific Islands.
sovereign: An independent or non-independent jurisdiction which itself possesses or whose people possess in their own right the jurisdiction's supreme authority, regardless of the jurisdiction's or people's current ability to exercise that authority.
possession: Equivalent to territory. Although it still appears in Federal statutes and regulations, possession is no longer current colloquial usage.
commonwealth: An organized United States insular area, which has established with the Federal Government, a more highly developed relationship, usually embodied in a written mutual agreement. Currently, two United States insular areas are commonwealths, the Northern Mariana Islands and Puerto Rico. A United States insular area from April 11, 1899, the Philippine Islands achieved commonwealth status on March 24, 1934 (Public Law 73-127), and remained as such until the United States recognized the Philippine Islands' independence and sovereignty as of July 4, 1946.
incorporated territory: Equivalent to Territory, a United States insular area, of which only one territory exists currently, Palmyra Atoll, in which the United States Congress has applied the full corpus of the United States Constitution as it applies in the several States. Incorporation is interpreted as a perpetual state. Once incorporated, the Territory can no longer be de-incorporated.
Territory: An incorporated United States insular area, of which only one exists currently, Palmyra Atoll. With an area of 1.56 square miles, Palmyra consists of about fifty small islands and lies approximately one thousand miles south of Honolulu.
unincorporated territory: A United States insular area in which the United States Congress has determined that only selected parts of the United States Constitution apply.
territory: An unincorporated United States insular area, of which there are currently thirteen, three in the Caribbean (Navassa Island, Puerto Rico and the United States Virgin Islands) and ten in the Pacific (American Samoa, Baker Island, Guam, Howland Island, Jarvis Island, Johnston Atoll, Kingman Reef, Midway Atoll, the Northern Mariana Islands and Wake Atoll).
organic act: The body of laws that the United Congress has enacted for the government of a United States insular area; it usually includes a bill of rights and the establishment and conditions of the insular area's tripartite government.
organized territory: A United States insular area for which the United States Congress has enacted an organic act.
unorganized territory: An unincorporated United States insular area for which the United States Congress has not enacted an organic act.
Compact of Free Association: The status of free association recognizes an island government as a sovereign, self-governing state with the capacity to conduct foreign affairs consistent with the terms of the Compact. The Compact places full responsibility for military defense with the United States. The basic relationship of free association continues indefinitely; the economic provisions of the Compact are subject to renegotiation at the end of 15 years.
Disputed Island: Formerly or currently considered U.S. possession by the U.S. The U.S., through negotiation, has disclaimed ownership of most islands in favor of another country. Two islands remain contested.