I understand what makes Front and rear caliper brakes different. Whats the difference between front and rear Cantilever Brakes?

Sometimes the orientation of the brake pads is different.

As Retro Grouch said, nothing save for the orientation of the brake pads.

Some Shimano brakes come with a different link wire for front or rear, but the brakes are the same. Some just come with the pads installed properly for that orientation.

I saw a bike set up with Avid cantilevers that had different arm lengths for the front+rear, but one of the brakes could just have been older than the other. New Avid brakes are sold as only one part that is "front/rear compatible".

I have seen Shimano BR-550 being sold as both front/rear and without specifying.

It's common to run wide profile brakes on the front but if you put the same ones on the back, you might hit them with your foot so you use ones that don't stick out so much.

Shimano used to specify front/rear just to ensure the brake pads were int he right orientation at the time of purchase, but if you swapped the pads left to right the rear are identical to the front.

THere also used to be Scott 'Self Energizing' brakes that were (as I recall) likely to grab uncontrollably and throw you over your bars if used on the front, but these have been off the market for a decade, I think.

Here's Universal selling the front brake for $9 more then the rear brake. ????
https://www.universalcycles.com/shopp...50&category=34

Mostly it's the pad orientation, but one exception was the M900 XTR center pull cantilever brakes. The front arms were longer than the rear.

Odd... I don't doubt that Shimano still ships them in boxes labelled "Front" and "Rear," but the retailer must have gotten a better deal on a batch of just "Fronts" or something. I just looked at the associated tech docs on the Shimano website, and there is no mention of front or rear specific, except ensuring the brake pads are in the correct orientation.

https://techdocs.shimano.com/media/te...9830677287.pdf

If you're doing a repair where service time is money, front/rear labelled brakes that have the pads in the correct spot saves time. As been beaten to death, there are no differences other than that between either front or rear canti/v-brakes for shimano.

Repairs, and even more noticable would be an assembly run where multiple bike with similar setups are to be built over the course of a day - the last thing you need is fiddling with tiny washers 4X for every bike - the process is not so complicated but the time it takes to go back and correct a mistake is the real kicker.

I'm setting up an old pair of SHIMANO ALTUS BR-CT91 cantilever brakes, and I've learned that the Shimano- branded link wire (like a pre-measured straddle cable) come in A & B sizes, which are front/rear specific: "A" Link wire is for Front brakes;
"B" Link wire is for Rear Brakes. I'm still trying to figure out whether the actual brake arms are different, and, if so, how to tell which ones are which.
Lots of info at "Boring McBoring's guide to shimano cantilever brakes (including all the McVersions...)" [I'm not allowed to post URLs or photos yet...]

15 year old...

one reason why Shimano chose different link wires (straddle wires by a different name and set up) was to deal with the different cable casing hanger/stop to canti dimension compared to the usual front. Often rear brakes (especially on smaller or ladies frames) had little space between the stop and the canti arm ends. So a long link wire would place the junction "button/yoke) too close to the stop and cause contact before full pad against rim was achieved. Front set ups usually had much more room between the (usually high located) casing hanger and the cantis. This greater room also allowed for the best link wire length for best leverage (and not a length compromised by clearance issues). Andy

Whiskey with that costs extra, just sayin'. A well-fermented and suitably aged thread. Savor the fleeting bouquet while it lasts.

They have different internals for front and rear, because the helical actuators need to turn in opposite directions. The front type was withdrawn because it was too easy for unwary riders to launch themselves, but they were fine in experienced hands; ISTR the rear version was available until fairly recently.

They are priced according to how much of the stopping they will do...

Is 15 years a new record?

People tend to forget that brakes are often better than they need to be.

At various times, Shimano and others have gone out of their way to de-tube or limit front brakes for the US market, out of fear of lawsuits over endos.

Discounting legal concerns, I'd arrange brakes so the front were stronger, however CYA thinking would indicate the opposite.

That's incorrect - there were several different length link wires, the correct one is determined by the spacing of the brake bosses and the rim width. The link wire arrangement was just a CYA from Shimano to stop broken cables locking up front wheels; instead use a regular straddle wire, and whatever retention system suits the bike - reflector or lamp bracket, mudguard, zip tie ...