If the material is the same then there should be little difference between brand name shoe trees unless they are a specifically shaped last for a specific shoe, i.e. when you buy bespoke shoes it is common place to recieve a pair of shoe trees specifically for those shoes as they will keep the shoe as close to its original and intended shape.
TIP: cedar shoe trees are the best for many reasons but bespoke shoe trees are often made from a range more luxurious woods for aesthetic purposes.