Terms: update, upgrade and migration are frequently mixed up by computer users. Some even believe upgrade and update are the same thing, whereas migration has something to do with animals or people moving from one place to the other. Nothing is more erroneous than this belief as far as IT is concerned.
Update means reinstalling a new version of the same program, provided that there is no point difference in the the version numbers. In other words, it might be installing CodeTwo Exchange Rules 2007 2 .1 on top of CodeTwo Exchange Rules 2.0.
Upgrade means reinstalling a new version of the program with different point numbers. In other words, it might be installing CodeTwo Exchange Rules 2007 2.0 on top of CodeTwo Exchange Rules 2007 1.0. Upgrades are usually payable, but the price is lower than the one you pay for buying the product.
Migration means moving from one product to the other one. It can be moving from CodeTwo Exchange Rules 2007 2.0 to CodeTwo Exchange Rules Pro 1.0. Migrations are also payable and the price of the migration is almost always lower than the cost of the standalone product.