I believe S is manual shift, ES has the ESP push button shift, Rubicon has a 499cc instead of 475, full auto, ESP and a Low gear, and Canadian Trail Edition, is the same as a Rubicon except it has progressive shocks and they are adjustable.
I assume what you are refering to are the letters that are part the model number i.e. TRX500FE, TRX500FM etc. Not to be confused with the ES model type catagorizing. I believe the "FM" models are all electornic shift but the "ES" is not part of the actual model number. The "FE" models are non electronic shift (foot shift). I have never seen an "FH" as part of the model number. There are "FA" "FGA" and a couple others for other Honda models but no FH that I cand find.
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