calculating # of days from install to remove by address

I'm a newbie to this group thanks for the awesome knowledgebase!

My question is what is preferred conditional formula to determine number of days from "add" to "remove" (in SERVICE TYPE column) based on ORDER # (ORDER # is same as SERVICE ADDRESS fyi).

Would you recommend using = DATEDIF and if so, how would the conditional part of the formula be written? I am struggling to figure out an elegant way (& scale-able!) to do this

sample data.jpg