There are a few sure signs. But sometimes the piraters are so good at making their labels/carts, that it's hard to tell. The label is the best way to tell the difference. It's a pirate if the label has no copyright (date and/or publisher), if the label isn't on the cart straight, if the game has an English name and it's not familiar to you, if the label looks shiny metallic/holographic, if the label shows a picture of a more recent game (like DKCountry or Pokemon, and if the label has any meaningless symbols on it. The plastic part of pirate carts are usually cheaper looking. You'll be able to tell the difference in real and pirated plastic after shopping around on eBay a bit.

Also, try this: HERE.

You're wrong! Konami had three cart versions: the standard Nintendo version, the black with the hole, and the bulky-square ones kinda like gold Punch-Out!! But you're right that each company had specific types of carts. Especially true for Taito (two types) and Bandai (one, I think).

Still, easiest way to identify a pirate is the label, especially for Famicom noob.