立りっ憲けん君くん主しゅ政せい体たい

• 君くん主しゅ制せい

  君主制 is a broader term for monarchy in general, while 立憲君主政体 specifically refers to a constitutional monarchy where the monarch's power is limited by a constitution.

• 共きょう和わ制せい

  共和制 is a republic, where the head of state is usually an elected president, contrasting with the hereditary monarch in a 立憲君主政体.

• 立りっ憲けん君くん主しゅ政せい体たい

  Standard kanji spelling for 'constitutional monarchy'.

• 立りっ憲けん君くん主しゅ制せい体たい

  Variant spelling with 制 instead of 政; less common but attested.

Compound of 立憲 (constitutional) + 君主 (monarch) + 政体 (form of government). The variant 立憲君主制体 replaces 政体 with 制体, a less common combination.