胡说 means someone say something nonsense, false, etc., which emphasizes that the information someone expresses is wrong, while 废话 is used when people complain that someone say something that is not worth mentioning. For example, if a guy is asked to make a self-introduction and he says that his mother is a female, then you can describe what he says as 废话, for it is a common sense that woman gives birth to babe. And 废话 can be used in another way. For example, if A and B are having a discussion about a specific topic, but A goes astray and talks about other stuffs, then B may command that A should 少废话 to draw back to the focus. However, what A talks about may not be wrong information itself. It may be correct, just not related to the topic and is not worthy of mentioning during the discussion. Hopefully it can be of some benefits for you.

胡说：say something not true exp： “爸爸喜欢上别的女人了”dady is loving with someone else “不要胡说，爸爸永远只爱妈妈”stop saying wrong thing。dady is always being love with mami 废话：say someting uesless “中国是一个很大的国家”china is a big country “废话，大家都知道”you say something uesless。everyone know that，china is a big country 埋怨to sb。 抱怨with someting

胡说 what you said is nonsense, like saying you are making things up. A： 你是不是喜欢她？ B： 你胡说，我根本没有那个意思。 废话 what you said is totally useless. I knew what to do. You did not need to say it at all. A：你吃完饭记得要刷牙。 B：少废话，我当然知道要刷牙。 埋怨 complain somebody about sth. eg:1. 他上学迟到了，他埋怨他的妈妈没有叫他早点起床。 2. 不要埋怨别人，想想你自己哪里做错了。 抱怨：complain about sth. or just complain. eg:他整天都在抱怨工资太低。 3. 别抱怨了，好好工作吧。

胡說：things said are bullshit or do not make any sense. Others make up the story or said something that you disagree. EX：你別胡說，事情不是你說的那樣。(Don't talk nonsense. Things are not like what you said). 廢話：rubbish (useless words). Things said can be true but you don't really find them helpful. EX: 你別廢話了，說重點。 (Don't talk rubbish. Please straight to the point). ---------------------------------------------------------------------------------- 埋怨：it is more like blame someone for something. EX: 他總埋怨爸爸沒有時間陪他。(He always blames his father for not spending some time with him). 抱怨：it is more like complain in English. EX: 你別再抱怨了，快點工作吧! (Stop complaining. Go back to work). If you can read Chinese, I hope you find this link helpful: https://zhidao.baidu.com/question/67592896.html (In short, you 埋怨 someone but you 抱怨 things)

其实很简单，如果口语或者不讲究这个的意思很近。如果非得说不同，只能是强调的侧重点不同：胡说强调说，而废话是名词，强调话。 埋怨强调不是个人，而抱怨则偏向个人发出来的怨气。希望能给你些启发。