Note, Most of this comes from an earlier answer

China was an anomaly in the Japanese imperial system. The Chinese inhabitants in Manchuria, Liaodong (a "leased territory" like Hong Kong), and occupied China were not formal Japanese subjects, but rather were nominally citizens of the various Chinese client states of the Japanese government. In practice, various Japanese military and civilian agencies tended to be the ones calling the shots in these areas. The result was a colonial order prejudiced in favor of Japanese interests at the expense of the native Chinese. One pernicious example of this exploitation was the Japanese creation and sponsorship of a Manchurian state opium monopoly as a means to bring in much needed revenue to the Manchurian state, which by extension meant the Kwantung Army. The creation of the client state of Manchuria led to an influx of a sizable number of Japanese settlers and economic combines. The outbreak of war with China in 1937 heightened this exploitation.

Taiwan and Korea were legally Japanese territories under the Japanese empire. When Japan began its imperial project, there were two basic models for imperialism: the British and the French. The British paradigm treated these colonial areas as dependencies of the crown with various levels of autonomy. The French form of empire was predicated upon treating colonial territory as a zone that could be turned into a part of France. After much debate within the imperial government, the Japanese opted for the French model between 1910-15. Like the French colony in Algeria, Korea and Taiwan were administratively linked to the metropole and governed as if they were part of Japan. Both Taiwan and Korea were subdivided into prefectures and its inhabitants had the legal rights and responsibilities of Japanese citizens, with the imperial government emphasizing responsibilities like conscription and hewing to a program of cultural assimilation that transgressed the rights of Taiwanese and Koreans. Additionally, the Japanese government did encourage settlement of these areas by Japanese and the state supported Japanese business investment in Korea and Taiwan.

However, even though these were new Japanese prefectures, the Japanese governmental circles still saw these areas in highly functional terms. Both Korea and Taiwan had to serve Japanese imperial interests and not vice-versa. There Japanese placed a priority on the development of heavy industry and mineral extraction that would help make Japan self-sufficient. Agricultural development was also geared towards export to the home islands. This was part of the reason why the 1944-45 and the immediate postwar period was an era of great hunger for Japan, it had lost access to a major source of its food. To be fair to the Japanese, they were far from alone in this imperial exploitation and its empire was comparatively more humane than its contemporaries (indices like Korean life expectancy and literacy went up, unlike British India). Koreans drafted into the Japanese military tended to do the drudge work and Japanese companies operating within these areas were quite exploitative. The bureaucracy and other imperial structures favored Japanese settlers over the natives. Even when Japanese imperial officials tacked to a pan-Asian course, they placed Japan first in its brotherhood of East Asia.

So, in a roundabout answer to the OP's question, after ca. 1915, the Japanese government really did not distinguish between these areas being new provinces and its exploitation of these areas.

Sources

Beasley, W. G. Japanese Imperialism, 1894-1945. Oxford [Oxfordshire]: Clarendon Press, 1987.

Duus, Peter. The Abacus and the Sword The Japanese Penetration of Korea, 1895-1910. Berkeley: University of California Press, 1995.

Myers, Ramon Hawley, Mark R. Peattie, and Jingzhi Zhen. The Japanese colonial empire, 1895-1945. Princeton, N.J.: Princeton University Press, 1984

Smith, Norman. Intoxicating Manchuria Alcohol, Opium, and Culture in China's Northeast. Vancouver: UBC Press, 2012.

Young, Louise. Japan's Total Empire Manchuria and the Culture of Wartime Imperialism. Berkeley: University of California Press, 1998.