But the exiled Republic of Ireland international could make his bow for his new club in Sunday's Premier League clash with Newcastle United.
MacDonald is convinced Ireland could have as much of an impact as 24-year-old Milner.
"He is a different kind of player to James with his power and strength all round the pitch, allied to a very good football brain," said MacDonald, who was handed temporary charge of the club following Martin O'Neil's shock decision to quit.
Milner's performances last season helped Villa reach the 2010 Carling Cup final and the semi-finals of the FA Cup.
The midfielder also landed the PFA young player of the season award and earned a call-up to England manager Fabio Capello's World Cup squad.
I still haven't particularly thought about it - I still haven't any feelings
Kevin MacDonald on the managerial vacancy at Villa
Meanwhile, MacDonald has admitted that he is unsure whether he would want to succeed Martin O'Neill as manager on a permanent basis.
"I still haven't particularly thought about it. I still haven't any feelings," he said.
"I keep saying that I'll know if I want it. At the moment I haven't got that, although I haven't had time to sit down and think about it.
"It has been a bit of a whirlwind, so I'll wait and see, but I just need to know it's going to be right for myself.
"If I feel I would like to be considered along with others, I will let owner Randy Lerner know in the very near future."
MacDonald added that he would have to speak to his family and seek their opinion before he made a decision.
"It's not just about me, it's about my family, becoming a Premier League manager is a life-changing thing," added MacDonald.
"It is upheaval for families because you never get to see them, you have to chase around, organise things, take phone calls and all that sort of thing, and that's another thing I have to look at."
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