さえEven

すら and さえ are both somewhat formal intensifiers that can be used in similar ways. For example, 子どもですらできる and 子どもでさえできる are both emphatic ways to say 'even a child could do it'. Though they can overlap in some usages, one difference is that さえ can be used with ば conditionals in expressions such as これさえすれば 'as long as you do this', while すら is not used in this way.

Both さえ and まで mean 'even,' but with different nuances. さえ is often used with negatives to express 'not even X,' e.g. 食べることさえできなかった ('I couldn't even eat.'). まで is usually affirmative and highlights something surprising or extreme, e.g. 骨まで食べた ('He even ate the bones.').

Both さえ and 割に convey, in some sense, a characteristic or event contrary to expectations. さえ is a strong 'even' that shows emphatic extremity or surprise, e.g. 子どもさえ分かる ('Even a child understands'). 割に expresses contrast with expectations, e.g. 年の割に元気だ ('He's energetic for his age').

Both expressions use さえ, but their usages and nuances differ. さえ〜ば shows that one condition is sufficient, like 'as long as (A)', e.g. お金さえあれば何とかなる ('As long as I have money, things will work out'). さえ alone emphasizes extremity, surprise, or unexpectedness, e.g. 彼さえ知らない ('Even he doesn't know').

さえ and ても can both express the meaning of 'even' and sometimes overlap, especially with nouns. For example, 子どもでもできる and 子どもさえできる both mean 'Even a child can do it.'. However, they diverge when ても expresses permission, such as in 行ってもいい ('You can go.') or when さえ means 'if only', e.g. お金さえあれば 'as long as you have money'. In these cases, the two expressions are not interchangeable.