A biotope is a section of an ecosystem, with everything coming from a specific location, not necessarily planted.
Planted is just that, a tank with plants.
Low tech typically means without CO2 injection or strong lighting.
There are some tendencies depending on who you ask sometimes.
Planted can also mean plants are the central thing, making it an aquatic garden. Many Aquascapes and "Nature Aquariums" fall in this category.
Biotope can mean it has to be an exact replication of an ecosystem, it can also mean it just LOOKS like the Biotope the animals in it come from. Blackwater tanks as well as specialized MalawI or Tanganyikan tanks would count in this category.
Some people say low tech has to be a sponge filter at best, no light besides sunlight and no heater.
High tech can mean anything from special growth lighting and CO2-Systems to fully automatic systems that do the water change for you.
So... most is a spectrum and very much depending on the individual you ask and in what context someone has heard the term first.