Electronica… too vague a term to define the genre. I’ll give you a couple that I tend to follow.
Hardcore: the general type of techno that tends to be more bass-heavy with many genres stemming from this.
Gabber (or Gabba): techno with some form of heavy/black metal and a variation of rap. Tends to go into dark themes, drugs, etc.
Terror: similar to Gabber except gets very dark, oftentimes relating to the devil or demons. Gets high up on the BPMs.
Speedcore: the bastard child of Hardcore and Gabber. Tends to get very fast, going over 160 BPM. It spawned a subgenre in New York, a.k.a. NYC Speedcore. Disciples of Annihilation are a great example of this. There are some other small DJs who go by this.
Jungle/Trip Hop: slow in comparison to most techno. It sounds more like rap with a house beat.
Trance: 4 words to describe this -> “the pop of techno.” That is to say, it seems nowadays that this is the only thing that is played at most raves. It has a dream-like sound that sounds like something out of a Tangerine Dream album with more bass.