For what I've been found, this two arts have some similarities, but I can't fully understand it, this is pretty much the definition of each.
Iaido: The art of sword drawing. All katas begin and end with the sword sheathed. In some ways you could liken it to preparedness at all times, not just in battle.
Iaijutsu: The art of drawing the sword, is one of the Japanese martial disciplines in the education of the classical warrior. It's a combative sword-drawing art but not necessarily an aggressive art because iaijutsu is also a counterattack-oriented art.
I'll be grateful if someone could tell me a relevant difference!
Thanks in advance!