The first sentence makes sense, but I would write: I didn't go so far as to call him a liar. The second sentence does not make much sense in this context. The phrase "as much as" is usually used in a compound or comparative sentence: As much as I like cats, I am allergic to them. I like dogs as much as I like cats. If someone has a better answer, please expand upon this one. (or make it better)

To me, the sentences are quite different. "I didn't go so far as..." means that you think calling him a liar is a BIG, IMPORTANT thing. "I suggested that he might have made a mistake, but I didn't go so far as to call him a liar. I didn't want to upset him." "I didn't so much as..." means that you think calling him a liar is a SMALL UNIMPORTANT thing. "I don't know why he is mad at me. I could have called him a fraud, a hypocrite, or a hundred other really awful words. But I just suggested he was mistaken. I didn't even so much as call him a liar."

"I didn't go as far as to call him a liar." "I didn't go so far as to call him a liar." These sentences are equivalent and correct. We use "as far as to ... [do something]" meaning "to [do something]" when [something] is risky, controversial, or extreme. It is usually used in the negative: "I wouldn't go so far as to call her ugly, but she isn't exactly a supermodel" "He didn't go as far as diving in, but he dipped a foot" "I didn't go as far as going to speak to him, but I stared in his direction a lot" We use "Not ... as much as ..." to correct or refine an incorrect or imprecise idea. For example: "I'm not so much angry with your behaviour as dissappointed" "She's not so much a doctor as a real-life superhero" "They're not so much studying as chatting near open books"

我也是自己造的，也不知道有无细微差别，我自己倒是觉得差不太多，哈哈

这两句话的意思一样吗？还是有细微的差别？如果没什么差别，我想就该能互换，有一点差别就不能互换，这真是个咬文嚼字的活，快来帮忙呀！