You want to go and look at them, I've looked at 25K mile/4 year old cars that have looked and felt unloved and shagged. The age/mileage difference between those two is neither here nor there compared to the general condition of the car. Also be wary of clocking.
Yes as others have said there's more to buying / choosing a car than the info in your OP, but given that everything else is level I'd buy the high mileage one.
The higher mileage is more likely to be correct ..
Everything being equal, I'd buy the car that's a year older with less miles. A few years down the line, a year's difference won't be as critical as with a newish car, but the offset in mileage will always be there.
Condition is important here,is the road tax different,when were they last serviced,are the tyres going to need replacing,are the alloys kerbed,is one due a major service or a cam belt etc.
Consider all the above you might have a easier time making the decision.
