Prerequisites for AIC/BIC model comparison

I have a question about model selection when using AIC/BIC. So, if two model structures are totally different, can I still directly apply AIC and BIC? Also, for a hierarchical model, how to compute the total number of parameters when computing AIC and BIC? Thanks.

• can you explain what you mean by model structures? – DataD'oh May 17 '14 at 22:34
• For Example, one is Multinomial Logistic Regression, another one is Hierarchical Gamma. – Cosmozhang May 18 '14 at 0:24