此外，means "besides", "in addtion to" for example:He gave me a book, a pen and some money besides. 他给了我一本书、一支笔，此外还给了我一些钱 而且，means " and", "but also" often preceded by"不但，不仅” for example: He can not only drive a car but also repair.他不但会开测，而且还会修理。

此外有转折的意思等于but，而且有并列的意思等于and ,两者都是对同一事物的不同观点的转述！

"此外" is written language.

此外是比较正式的说法，一般用在演讲或者写作里，有“除此之外”的意思。而且比较口语化，可以和不但连用，比如：他中文不但说的好，而且表达也很清楚。

此外, it's short for "除此以外" means "in addition to", "plus", "besides" and so on. it always use before a sentence. 而且, means also, it's the same to 此外 sometime. but, 而且 always decribe the same thing. but “此外" always means different things. it always a stop after word “此外”. i.e: 我今天去了长城，而且也去了故宫，此外，我还去看了场电影。