What is the difference between a Rube Goldberg and a Heath Robinson?

Heath Robinson was an English cartoonist "whose cartoons of crazy inventions soon captured the public imagination. Essentially he was caricaturing the age of the machine and the self-importance of some of the people caught up in that age - creating complex inventions that achieved absurdly simple results, while the audience looked on solemnly. The term 'Heath-Robinson contraption' came into official dictionary use in around 1912."

http://www.bbc.co.uk/history/historic_figures/robinson_william_heath.shtml

"Reuben Garret Lucius Goldberg (July 4th, 1883 – December 7th, 1970) was an American cartoonist, sculptor, author, engineer, and inventor who received a 1948 Pulitzer Prize for his political cartooning. He is best known for his series of popular cartoons depicting Rube Goldberg machines, complex devices that perform simple tasks in indirect, convoluted ways."

https://en.wikipedia.org/wiki/Rube_Goldberg

The two terms refer to the same sort of devices, but produced on different sides of the Atlantic at different times, and with different satirical points being made by the cartoons.

W. Heath Robinson was also a brilliant serious illustrator of other people's books. This work is overshadowed by his purely comic - no, not purely comic but often gently satirical - cartoons. Look at http://www.johncoulthart.com/feuilleton/2008/02/20/william-heath-robinsons-midsummer-nights-dream/ for one set of examples of the other side of WHR. I don't know about Goldberg, but WHR did a lot of advertising work in the comic style - taking the mickey out of the firms employing him and increasing their sales at the same time. That probably wouldn't work in the USA where advertisers take themselves rather too seriously...