Humans (2015) is a joint British and American production from AMC and Channel 4, adapted from the original Swedish series Real Humans (2012) which lasted two seasons. I have seen the first season and part of the second of the Swedish series but without subtitles so I might miss some parts.
Both series deal with Synths/Hubots, robots that co-exist with humans and are helpers (nannies, cleaners, etc.) but there are more active A.I.'s along with Leo, who is a hybrid thanks to his father, the creator of the Synths. Leo is on the run with his 'siblings,' Synths that are aware with one killer Synth. Anyway, some things are rearranged. This contains spoilers, where Leo doesn't reunite with his 'siblings' in the original version. The main family, the Engman family didn't help out the active Synths while the Hawkins did. Dr. George Millican's (William Hurt) counterpart Lennart Solberg in the Swedish version was related to the Engman family but he did have his Hubot Odi, same name in both versions. Also D.S. Pete Drummond is a mixture of two characters, of Leif Andree, who had a wife who was into her Synth/Hubot but he wasn't a detective.
There was much more characters in Real Humans and a lot of storylines were shorten and dumped in Humans. For example, the conscious Hubots have more storyline of hiding from people. Also Roger's wife Camila, which is Peter's wife's counterpart has a longer storyline about being with her robot and she has a friend that is married to her robot. Also there is a whole subplot of Odi being with traffickers and criminals.
Leo Eischer/Leo Elster
In Real Humans, played by semi-famous Sweish actor Andreas Wilson and in Humans, semi-famous Colin Morgan (Merlin). Both handsome fellows who their fathers David were robot creators. Leo drowned and was saved by their father and was made into a hybrid. He sought his siblings. In Real Humans, Leo died in the end of season one and didn't reunite with Mimi/Anita. Mimi/Mia was his mother figure.
Mimi/Mia/Anita
Both were named Anita by their families. Both were mother figures to Leo. Both were made to have other programs to replace them. I am not sure about season 2 of Real Humans but Anita did not turn back into Mimi in season 1.
Inger Engman/Laura Hawkins
Both heads of households, both lawyers, both uneasy about Anita. I am not too sure about Inger because I don't know Swedish and didn't see the show subbed. Laura eventually gets on the side of Mia once she sees it for herself who she is.
Hans Engman/Joe Hawkins
Both brought Anita home. Joe had sex with Anita while I don't think Hans did. The Engman family was all blonde while the Hawkins family is mixed when Joe is ginger, Laura has reddish-brown hair and all their kids are brunettes but Sophie is dirty blonde.
Tobias Engman/Toby Hawkins
Both teenage boys, both had a thing for Anita. But Toby was more innocent as Tobias actually felt up Anita in Real Humans and saw her naked.
Matilda Engman/Matilda Hawkins
Both are eldest child of the family. Both hackers but Mattie is much more so in Humans. Both hacked into Anita. In Real Humans, Matilda worked at the supermarket where Odi broke down.
Sofia Engman/Sophie Hawkins
Both the youngest, both bonded with Anita.
Lennart Solberg/Dr. George Millican
Both elder men who have a robot named Odi. Lennart was related to the mom Inger in Real Humans while unrelated to the Hawkins in Humans. Both are given rougher female model robots to replace the broken down Odi. George worked for Leo's dad David and has more connection to the Synths. In Humans, he is played by William Hurt and is killed. As of season 1, Lennart was alive.
Odi
Lennart's beloved but broken down Hubot. He is stolen and reprogrammed for criminals which continues into season 2 of Real Humans. In Humans, he is just abandoned and returned to George, he had memories that helped George.
Roger/Ove/D.S. Peter Drumond
Engman's neighbor Roger works at a Hubot warehouse and lives with his wife Therese and step-son Kevin (who has his own plots) in the beginning of the series. Camila then begins a relationship with her hubot Rick. She moves out. In Real Humans, he is a detective and only alludes to his wife Jill with being with her Synth. Peter almost has a relationship with Karen. Peter is a combo of Roger and Ove, a detective in Real Humans.
Niska
In Real Humans she is the leader of the conscious Hubots and killer. In Humans, she worked as a prostitute, was a killer but then resentful for it. Even sort of bonds with Sophie. Humans' Niska is a mix of two Hubots from Real Humans, as another was a prostitute.
Max
Both followed Leo around but in Real Humans, Max did not have free will yet and was destroyed. In Humans, Max does have free will and sacrifices himself for the others.
Bea Novak/Karen Voss
Both are detectives that turn out to be robots that were designed to look like Leo's dead mom. In Humans, she betrays the other conscious robots. In Real Humans she does speak to Niska from time to time. In Real Humans, she bonds with Roger and in Humans, she sort of has a connection with Peter, Roger's counterpart.
