These seem to be the same things? If any gardening gurus want to chime in it'd be appreciated. Though at the moment they seem to be almost identical results across all four tags. I think we only need two one for large two handed ones and one for the smaller scissors you'd use for a tomato plant.
(1) An individual device would be called a "hedge trimmer" singular, unlike clippers, shears, or scissors.
(2) The hedge trimmer term is broadly used to cover both motorized hedge trimmers and manual hedge trimmers, but more commonly is used to refer only to the motorized trimmers. Noted for example with wiktionary defining it only as a "A portable electric saw designed for trimming hedges." Hardware stores like Home Depot or Lowes use the term "Hedge Trimmer" only for the motorized device and use the term "Hedge Shears" for the scissors. Home Depot will make the suggest of either searching "Hedge Trimmer" or "Hedge Shears" if you try searching "Hedge Clippers." Lowes will simply display it all, but will display more specific categories of "Hedge Trimmer" or "Hedge Shears" to narrow down the results.
(3) "hedge trimmer" is significantly more common a term than "hedge clippers" with "hedge trimmer" generating about 10,800,000 results on google versus the about 566,000 results for "hedge clippers". "hedge shears" for reference generated about 1,410,000 results.