Updates are version series patches and enhancements
which do not usually require a current user to upgrade his use
license. If for example you have a version 2.5xx series of a product
then all updates within that series will work with your license
for that specific product and series. These updates are usually
free when downloaded from the website.
Upgrades are significant product enhancements
and will usually have a significant version number change. These
newer versions will require existing users to upgrade their user
license if they want to use the newer versions. There will be
an upgrade fee associated with the license upgrade.
If you continue to use an older version for which you are currently
licensed, then that license will continue to work and will not
be affected by the fact that newer version products are available.
This means that the older versions will continue to work as long
as you have the appropriate OS and hardware on which to run these
older versions. However when web protocols change, which may affect
communication over the web, this could result in the need to upgrade your
hardware and software as a result of web based protocol changes. When the
latter happens there is no other option other than Upgrade.