The existing differences existing between an active and a passive DisplayPort converter should properly be considered when converting a video from any source that makes use of mini DisplayPort to DVI. For instance, a computer to another monitor. If a dual-mode DisplayPort or a DP++ is supported by the source, then a passive adapter should be used, in as much as the source can do the conversion. But where dual-mode DisplayPort or DP++ is not being supported by the source, then the active converter is recommended because it includes additional conversion chips. Thunderbolt ports support DP++ in some sort of way (natively).
The fact that this type of adapters does not include any additional conversion chip tends to make it less expensive. If you intend finding out if the passive adapter can work for you, then check if the DP++ symbol is above the mini DisplayPort source. This symbol is shown as a D and a P inside it with double + signs to the left, with one above the other.
This type of adapter makes use of an additional chip for making conversion within the adapter, whether DP++ is supported by the source or not. This type of adapters is more expensive than the passive adapter types. If you have plans of using different monitors but with one particular computer then the active adapter is best for you, this is because most video cards are incapable of running the maximum monitors number when DP++ is in use. This can be attested to when the computer possesses two or more mini DisplayPort active connection. You can also find out from your video card supplier to make sure you know the adapter type needed for the setup you desire to run.