Commuting - hybrid? cyclocross? tourer? for commuting

can anybody please tell me what the actual differences are, among a hybrid, a cyclocross and a tourer?
at the moment I am commuting on my dad's bike, a diamond back parkway, 90's I guess.
I saw it listed at diamond back's website, as a cyclocross. equipped with upright handlebars, 700x38, originally, but I have added fenders, and a rack.
If I was not telling you these specs, how would you know if it wasn't a tourer, from the looks, alone?
Would the three types I mentioned ride and feel differently?
thanks.

All of these bikes are capable of general purpose commuting.
The more specialist (CX/touring) styles are generally only made in higher grades with better materials and workmanship so are more expensive.
There are differences in
wheelbase,
steering agility,
the variety of frame attatchment points (for racks and waterbottles, cable runs etc),
the height of the bottom bracket (for ground clearance vs stability)
tyres and fender clearance.
IMHO, a full expedition touring bike is overkill for the commute.
Medium and light touring bikes and touring style CX bikes are ideal.
The modern style of flat-bar road bike (Specialzed Sirrus types) are also pretty good and better than the typical hybrid.

Usually the word hybrid refers to low end bikes that are supposedly "hybrids" of road and mountain bikes, but the only common denominator is that they don't have drop handlebars. This category seems to have been mostly replaced with the category of "comfort" bikes. Which are bikes for people who are afraid of bikes. The sportier version of hybrids are now "urban" or "flat-bar road bike".

Cyclocross bikes and touring bikes are similar in that they usually have drop handlebars, cantilever brakes, and no suspension. (A few have disc brakes or V-brakes). The main differences between a "pure" cyclocross bike and a touring bike is that the cyclocross bike will have a quicker turning, shorter wheelbase and gear ratios that are not suited for climbing hills with a full load of gear. The touring bike will have longer seat stays for stability and heel clearance when rear panniers are mounted as well as lots of attachment points for racks, fenders, and water bottles. Since cyclocross bikes and touring bikes are so similar, there are bikes that are in between and could be used for cyclocross racing or touring, the Bianchi Volpe, for instance.

Usually the word hybrid refers to low end bikes that are supposedly "hybrids" of road and mountain bikes, but the only common denominator is that they don't have drop handlebars. This category seems to have been mostly replaced with the category of "comfort" bikes. Which are bikes for people who are afraid of bikes. The sportier version of hybrids are now "urban" or "flat-bar road bike".

Cyclocross bikes and touring bikes are similar in that they usually have drop handlebars, cantilever brakes, and no suspension. (A few have disc brakes or V-brakes). The main differences between a "pure" cyclocross bike and a touring bike is that the cyclocross bike will have a quicker turning, shorter wheelbase and gear ratios that are not suited for climbing hills with a full load of gear. The touring bike will have longer seat stays for stability and heel clearance when rear panniers are mounted as well as lots of attachment points for racks, fenders, and water bottles. Since cyclocross bikes and touring bikes are so similar, there are bikes that are in between and could be used for cyclocross racing or touring, the Bianchi Volpe, for instance.

Props, Thor, very good explanation.

If you are interested in a cross bike for commuting, check out this thread (http://www.bikeforums.net/showthread.php?t=155135), which I started to solicit opinions on these bikes. Some very informative posts there.

And for what it's worth, I'm leaning strongly towards the Surly Cross-Check (http://www.surlybikes.com/crosscheck.html). It's not a high-zoot race machine, but a do-it-all bomber.

There is one more difference. Touring bikes will have a shorter top tube than a cyclocross bike, meaning that touring bike has a more upright riding position.

Go to the Surly website (http://www.surlybikes.com/main.html) and compare the Cross-Check's (http://www.surlybikes.com/crosscheck.html) geometry to the Long Haul Trucker's (http://www.surlybikes.com/longhaul.html) if you want an example.

Terrain and budget please ....


Get the stronges, lightest, easiest to roll bike you can afford. Regardless, I advocate for only one gear, fixed if possible.

Thor29's post is succinct and replaces pages and pages of information compiled from here and elsehere. Wished I would have read Thor29's passage several months ago.

I have been following both threads on Cyclocross bikes. I have a Marin MTB that has a very light (for a MTB) yet sturdy frame and no suspension. It seems to me that if I added drop bars and thinner tires I would be very close to a cyclocross bike. Am I right about this?

But a touring frame is soooooooooooooooooooo comfortable; like loving a big fat woman.

Cheers

My touring bike is heavier than my CX bike, and it doesn't ride smooth until it's fully loaded with 30+ lbs. of gear (needs more weight to flex) . Both have an equally comfortable riding position. I'd say get the CX bike unless you want to tour.