[R] nnet classification accuracy vs. other models

[Albedo]

I was wandering if anybody ever tried to compare the classification
accuracy of nnet to other (rpart, tree, bagging) models. From what I
know, there is no reason to expect a significant difference in 
classification accuracy between these models, yet in my particular case
I get about 10% error rate for tree, rpart and bagging model and 80% 
error rate for nnet, applied to the same data.

Thanks.