Well rikudou senjutsu is just a different type of senjutsu from Hashirama's, frog sage, and dragon sage. There's different types but they are the basis in which you need to take before going through the standards to get rikudou senjutsu. Rikudou chakra is also all the same.
Rikudou chakra
1. Be an oototsuki family such as kaguya and Hamura. All have rikudou chakra.
2. Ashura+Indra chakra together or Hagormoo's chakra given directly. (benefits are rinnegan awakening by indra incarnates)
3. Juubi gives off some rikudou chakra (cause kaguya is juubi)
4. Uchiha+senju inherit both yin and yang of the sage gives you the power of the sage
Rikudou senjutsu
1. Born from kaguya inherit some senjutsu like Hamura and Hagormoo(pre JJ) did.
2. Juubi Jinchuuriki gives a lot of senjutsu/natural energy
3. All nine bijuus chakra gives you rikudou senjutsu (if you already have sennin mode perquisite like frog sagemode)
4. Hagormoo gives it to you directly but need sennin mode perquisite before taking that next step.