您好，in addition to和in addition都是很常見很常用的短語,都有“除了、還有”的意思,但它們的用法是完全不同的, In addition to整個片語相當於一個介詞,所以to的後面要接賓語.例如:In addition to native plants,this garden contains numerous trees and flowers from overseas.除了當地的植物之外,這座花園還有無數來自海外的花草樹木.In addition相當於副詞,通常放在從句的句首,後面接完整的句子.例如：This garden has the best collection of native plants.In addition,it contains numerous trees and flowers from overseas.這座花園有當地植物的最佳珍藏.另外,它還有無數來自海外的花草樹木.許多詞可以和它替換,如：additionally,furthermore,besides.

in addition另外,此外=besides;what"s more 等用法通常結尾用逗號.例如;

In addition, they hunted wild cattle, pigs and horses and made use of many wild plants.

除此之外,他們還會狩獵野生的牛、豬、馬,並且懂得利用許多野生植物.

in addition to： 加之.to後常加名詞或代詞等,如:

In addition to English, there are some materials in French, German, H pu india, Portuguese and Spanish. 除了英語,還有一些材料是法語、德語、北印度語、葡萄牙語和西班牙語的.