Her failure was due to her inability to get the job done. I could also say: she failed， because she was unable to get the job done. As you can see， the grammar is somewhat different. Because is connecting two complete ideas， while due to (similar to because of) is often used as a kind of compound preposition to finish one complete idea.
她的失敗是由於她不能完成這項工作。我同樣可以這樣說：她失敗了，因為她不能完成這項工作。正如你所見，語法在某些情況下會有所不同。Because用來連接兩個含有完整意義的句子，due to（跟because of意思相近），一般和to組成介詞詞組來完成一個完整的句子意思。 （原標題：Due To）