Update vs Upgrade
Updates in computer hardware and software are patches of code that are released in order to address certain issues or to activate specific functionalities. The need to release an update stems from the fact that there are certain problems that are not apparent before the product is released. The manufacturer only discovers the problems once users report and request for help. An upgrade is the act of replacing your product with a newer, and often more superior, version or similar product. Therefore, an update modifies your current product while an upgrade totally replaces it.
When it comes to the frequency, upgrades happen a lot less often compared to updates. A necessary part of an upgrade is the addition of new features; the development of which takes time. Most respectable companies address problems quickly. Because of this, you are likely to find more than a few updates available as they come up with solutions for each problem.
For commercial software, there is also the issue of cost. Updates are always free as they are not distinct software but are only meant to modify a pre-existing installation. On the other hand, upgrades are distinct and do not need the older software to function. You can expect to pay full price for the upgrade, though some offer discounts for those who own the older version. This is not really applicable when it comes to free software as they do not cost anything to use in the first place.
When a new update is released, people are encouraged to download and install it to solve or prevent the problem. This is even more important when the update addresses a security flaw in the software that may be exploited. An upgrade only offers new features and most users who are satisfied with what they have or do not see the need to spend more, could refuse to buy the newer version. A lot of people often skip every other upgrade to minimize cost while still being able to catch-up every now and then.
Summary:
1. An update is a patch that is made available after the product has been released, often to solve problems or glitches, while an upgrade is the replacement of an older version of one product to a newer one
2. There could be many updates for a certain product but only few upgrades
3. Updates are often free while an upgrade would cost money
4. Updates are often necessary while upgrades are not