There are two main categories of tree pruner, manual and electric. However, within these there are single bladed and double bladed pruners.
Single Bladed Tree Pruners - these have a solitary blade and use a saw type cutting action to cut through tougher, larger branches. (see image below)
Single Bladed Tree Pruners - these have a solitary blade and use a saw type cutting action to cut through tougher, larger branches. (see image below)
Manual Folding Single-Bladed Tree Pruner

The manual versions are basically manual saws (See image above) whereas the powered versions are long and generally like mini chainsaws on poles. (See image below)
Powered Single-Bladed Pruner

Double Bladed Tree Pruners - these are like extended secateurs or loppers and
are suitable for smaller branches. (See image below)
Double-Bladed Tree Pruners
These tend to be manual.
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