English explanation: http://www.bbc.co.uk/worldservice/learningenglish/grammar/learnit/learnitv56.shtml
because, because of, due to, since, for 的區別:
從句子結構方面：
-because 加句子
-because of 加一個短語
-since 加從句
-due to 加短語
-for 加從句
從幾個詞本身的意義方面：
1. because 是導致某結果的直接原因，一般是有這樣的因才有那樣的果。Because I am poor, I can’t afford it.
2. for 通常是先果後因，一般前面是猜測，後面for提供依據。
It must have rained last night, for the ground is still wet.
3. due to 向來是形容詞，作介詞不是傳統用法，而作容詞的due to只可用在be (或is、was等be的變體)之後，例如﹕
His failure was due to his laziness.
“Due to his laziness (adjectival phrase)” is modifying “his failure.”
4. because of 是複合介詞，其後接名詞、代詞、動名詞、what 從句等。*
I feel cold now because of the freezing AC.
“because of the freezing AC (adverbial prepositional phrase)” is modifying/explaining “I feel cold now.”
*due to + 名詞 = because of + 名詞
In informal modern English, due to n. = because of n.; however, many grammar nazis will hunt you down and lecture you for hours if you commit this “mistake.”
Source: http://words.journalism.ku.edu/because.html
5. since多為陳述性的事實，相當於“既然”：
Since you are busy, I will go without you.
Since the earth is round, why don’t we fall off it?
Sources:
http://bulo.hujiang.com/question/99037/
http://grammar.quickanddirtytips.com/because-due-to-since-as.aspx
http://lsdnes.pixnet.net/blog/post/33025574-because,because-of,since,due-to,for%E4%B9%8B%E9%96%93%E7%9A%84%E5%8D%80%E5%88%A5
http://www.indiastudychannel.com/experts/16771-what-difference-between-because-due.aspx
http://oald8.oxfordlearnersdictionaries.com/dictionary/due
http://oald8.oxfordlearnersdictionaries.com/dictionary/because+of#because
http://www.dailywritingtips.com/owing-to-vs-due-to/
http://www.tesoon.com/english/htm/14/65059.htm
http://www.bbc.co.uk/worldservice/learningenglish/grammar/learnit/learnitv56.shtml
http://www.jxenglish.com/Article/vocabulary/10150.html
http://www.uhv.edu/ac/newsletters/writing/grammartip2005.05.31.htm
心智圖詞彙攻略: https://bit.ly/2OcAJTb