there is no difference between,both words mean 'how'. but “怎么样” can be used in negative sentences , instead of the action or situation you can not say it directly , it is a euphemism for example,His article is not very good.（他写的文章不怎么样） in this situation ,we often not use "怎样" in our written language. In some degree,you can say 怎么样 is more euphemistic than 怎样. ---- and 如何, it means 1.how ( in what manner or way; by what means ) eg:How does this machine work?这台机器是如何（怎么、怎样、怎么样 any of them is ok) 工作的？ 2.in what state or condition. ---- 怎么： 1. how( for what reason or purpose; why.) eg:How is it that he left early? 他怎么离开得怎么早 2.express extent eg:He did not like you very much. 他不怎么喜欢你 3.however( we often use “无论”、“不管” and other words in front of 怎么，and put “都”、“也”ect. behind.) eg:He is very tired,and his mother asked him for sleeping many times, however he ... 他十分疲惫，但是无论他妈妈怎么要求他，他都不愿意去休息。 4.used in a rhetorical question or exclamatory sentence, express affirmative, negative , or emphasis eg:怎么，你没认出我？Whaat, you did't recognize me? ---- yes,as naomi said,啥 is a dialect in the northeast of China. and as you know it just means what~ you can just change the “什么” in the sentence into “啥” ，that''s ok. for example:你什么意思 ？（ What do you mean） 你啥意思？

example : 1 A： 那是啥 B：那是狗。 2 . A： 你为啥不高兴？ B: 我肚子疼。 3 . A： 我不想看书了。 B: 为啥？ A ： 我困了 4 . A ： 你干啥呢？ B： 我在看书。 A：你有啥书？ B： 我有中文书。 4： A ： 你怎么了？ B：没啥啊 A：你有啥说啥吧，没关系，我们是好朋友 B：真没啥，谢谢关心

如何：how，what代词。怎么；怎样；怎么办 how are things with you?你近来情况如何？ 怎么：how，what询问性质、状况、方式、原因等 What's all this about?这是怎么回事？

如何=what do you think 怎么=How 如何 and 怎么样 both have the meaning of asking someone's advise. 啥 is a dialect in the northeast of China.We usually say 什么 in a fomel way