What are the meanings of the terms mayavad and tattvavad? What are the differences between them?
Mayavada is used by some commentators to refer to Advaita Vedanta because as per Advaita everything perceivable through senses is Maya, including the world, scriptures and personal God. The only thing that is true is Nirguna Brahman.
Now this is a subtle and sensitive topic, and different seekers have different views, hence cannot be generalized. As an example, many traditional Advaitins e.g. Smartha acharyas accept the authority and existence of scriptures and personal God, as 100% genuinely real, but on a lower plane than the Nirguna Brahman. Adi Shankaracharya has mentioned in his commentaries "Release occurs only due to the grace of Bhagavan Vasudeva."
TattvaVada refers to Dvaita Vedanta, which accepts the world, scriptures and personal God as absolutely real.
Dvaita Vedanta (/ˈdvaɪtə vɪˈdɑːntə/; Sanskrit: द्वैत वेदान्त) is a sub-school in the Vedanta tradition of Hindu philosophy. Alternatively known as Bhedavāda, Tattvavāda and Bimbapratibimbavāda,