I'd say that at least half of the pitches I see include a slide comparing the presenting company's product to the products of its competitors. You've probably seen the slide... it lists the product names in columns at the top and the product attributes running down the left hand side of the slide. Each product gets some sort of score for each of the product attributes (a check or a filled in circle or a value). Not surprisingly, the product of the presenting company gets all the checks or circles or best metrics and its competitors don't. And for some reason the presenting company's checks always get to be in bold or a special color. I've even seen them animated.
Now I don't object to the slide. I actually think it can be a very effective way of pointing out the comparative strengths of a company's product with that of its competitors. The pitfall I see frequently is the attempt by a company to distinguish its product from a competitor's on bogus grounds. They'll list a handful of important features against which the competitors stack up favorably. But then they will list a number of less relevant factors simply so they can give themselves check boxes while leaving their competitors wanting (e.g., 5 USB Connectors, LCD Display, Accounting Expertise, Product Named After A State Bird, etc.).
While it may give the visual impression of greater differentiation, I strongly recommend you err on the side of conservatism. If it wasn't an important enough attribute to discuss when you were describing your product and its benefits, it isn't sufficiently important to put in this slide either. The things that differentiate your product should truly be different and those will be the things a venture investor will focus on. The other stuff is window dressing and it very rarely helps your cause.