The words especially and specially, have just a hair's breadth of difference between them. Both can be used to mean "particularly." Especially tends to be more formal, while specially tends to be more informal. Especially carries with it a sense of something exceptional, implying that there is something else that is of lesser quality. Example: We came to win the game and I thought we played especially well in the first half. Specially can refer to something with a distinct purpose, someone who stands apart from the rest, without insinuating that there is something or someone who is lesser. Example: Specially trained dogs may be useful in helping to calm autistic children.

"Especially and specially are adverbs. Especially means ‘particularly’ or ‘above all’: She loves flowers, especially roses. I am especially grateful to all my family and friends who supported me. We use specially to talk about the specific purpose of something: This kitchen was specially designed to make it easy for a disabled person to use. He has his shirts made specially for him by a tailor in London. Especially can also be used to mean ‘for a particular purpose’: I bought these (e)specially for you."

These words are very similar to one another and most people won't notice if you use them interchangeably. However, they are not identical. "Specially" is used to describe something that is particularly distinguished or superior for a particular purpose. "This brand of car is specially made for speeding" "Especially" is used when there is a possibility of different performance or quality. "This brand of car is especially good for speeding." It is possible the car is not particularly good for speeding. In all, the difference is a question of if something was made with a particular superior purpose (specially) or if something is being comparatively better at a particular action (especially). But as I said, most people won't notice if you use them interchangeably, but there is a difference.

Especially= Mostly, significance Example: I become tired especially late at night. He is especially smart in Science. Specially= correct, specific, custom Example: The charger is specially fit for the i-phone. She is specially trained to detect criminals. Great question, I speak English and this is the best definition I can think of in my own words :)

In informal spoken English, they are interchangeable.