这几个词的区别大致可从以下几方面去看：
1、therefore adv.因此, 所以=for that reason=consequently常用于连接两个并列分句,其前加“and”或分号“；”.
He was ill, and therefore could not come. 他病了, 所以未能来.
He has broken his leg and therefore he can't walk.他摔坏了腿,因此不能走路了.
We do not have enough money. Therefore we cannot afford to buy the new car.我们的钱不够,因此买不成这辆新车.
therefore用法:
therefore有两种用法,一在整句中,一在分句中.therefore是副词,但有时具有连词作用.
一、整句中时一般不放句末,句首后要有逗号,句中1、按一般副词使用2、做插入语（这两个分得清吧）
eg.1、Therefore,we must learn English well.
2、They therefore can learn English well.
3、Many fast food restaurant ,therefore,have red furniture or walls.
二、用在分句中,即一个句子一部分表示原因一部分表示结果.
这时一般词前要用分号,其后用不用逗号无所谓.若第二个分句前是逗号或无符号,则要注意therefore是副词,和so不一样,要保持句子完整,应用and therefore.
eg.1、I had a headache;therefore I could not go to your party.
2、I was ill,and therefore could not come.
3、These birds are very beautiful and therefore liked by many people.
2、so conj. adv因而, 所以, 结果是
It was late, so we went home. 天晚了, 所以我们就回家去了.
He was sick, so they were quiet.他病了,所以他们很安静.
3、hence adv.因此, 从此
The town was built among the hills, hence the name Hilltown. 该城镇修建在群山之中,故取名'山城'.
It is very late; hence you must go to bed.时间已经很晚了,因此你必须睡觉去.（记住前面是分号,而不是逗号）
4、then adv因此,就
Go into the cave, then they won't see you. 躲进洞里去,那他们就看不到你了.
5、accordingly adv.因此, 从而；所以,因此结果；因此（偶作连词使用conj.）
He was asked to leave the city and accordingly he went.有人叫他离开该城市,所以他就走了.
You may arrange accordingly.你可以权宜处理.
Mr Foster has never been to China. Consequently / Hence he knows very little about it.福斯特先生从未去过中国,所以对中国了解得很少.
My car was broken down and consequently I was late. = in consequence
6、thus adv.如此,像这样；因此；于是
He sold his farm and thus he had enough money for his journey.他卖掉了农场,这样他就有足够的钱旅行了.
There has been no rain — thus, the crops are drying.天没下雨,因此庄稼要枯死了.
accordingly,consequently,hence,so,therefore,thus
这些连接副词均有“因此，所以”之意。
accordingly书面用词，强调根据某种原因而得出的结果，其前可用冒号或分号，但不用逗号。
consequently正式用词，侧重符合逻辑的结果。
hence较正式用词，指接下来的东西是理所当然的必需的东西，但强调其重要性。
so用于比较随便的场合，口语中多用。
therefore通常指引出一个推断出的必然结论。 thus多用于书面语中，可与therefore换用。