と言(い)ってもAlthough ~ might say that ~

といえども is essentially a more formal/written-style variant of the more casual/colloquial と言っても, with both meaning 'even if one says'. Though they can overlap in usage, と言っても is perhaps more commonly used when referring to something actually said, e.g. 安いと言っても5000円はする ('Although I say it's cheap, it does cost 5,000 yen.'), while といえども is often used figuratively with no explicit sense of quotation, e.g. 名人(だ)といえども失敗する時もある ('Although he's a master, he sometimes fails.').

Both ～と言っても and にしても can be translated as 'even though' or 'even if', but they differ in nuance. ～と言っても is used to downplay or soften expectations, e.g. 運動と言ってもウォーキング程度です ('Even though I say exercise, it's just walking'), while にしても has the nuance of 'even considering (A), (B)' or 'no matter if (A), (B)', e.g. 忙しいにしても連絡してほしい ('Even if they're busy, I'd at least like to be contacted').

While both relate to things that have just been mentioned, ～と言っても softens or qualifies assumptions, while といえば introduces a related topic. For example, 旅行と言っても日帰りだった ('Even though I say vacation, it was just a day trip') vs. 夏といえば海ですね ('If we're speaking of summer, the beach comes to mind').

～と言っても typically qualifies or corrects an impression based on a previous statement, while ～というのは explains or defines something more directly. For example, 忙しいと言っても一日中じゃない ('I say I'm busy, but not all day') vs. 留学というのは海外の学校で勉強することです ('What we call study abroad means studying at a school in a foreign country').