1,special 和especial都是形容词,意思相同,可以互换.special是常用形式,especial多用于书面语.

2,specially 和especially尽管都是副词,但是意思差别比较大.especially 相当于in particular,意思是“特别地”；specially 相当于on purpose,意思是”专门地,特意地“.如：

He came home early specially to see his parents before bedtime.

He came home especially early.