They are actually usually quite different. Sophistication usually refers to 'style', but can also mean 'complicated', whereas 'intelligent' refers to mental ability. "She is very intelligent, she designs turbine engines". "He is very sophisticated, he dresses well, he knows his wine, and only goes to the fashionable restaurants" "This instrument is very sophisticated, you just put the sample in, and it does all the tests automatically" An intelligent person can be quite naive, or awkward, and therefore not sophisticated.

"Intelligent" refers to things like problem-solving ability, intellect, ability to analyze. "Intelligent" is connected to words like "think" and "brain." It does not refer to fashion or social skills. "Frederick Banting, the discoverer of insulin, was highly intelligent; but, despite being a Nobel prizewinner, he was unsophisticated and almost childlike." "Sophisticated" often means someone who is very experienced, very adept, and very up-to-date in social skills and trends. It means someone who can do advanced or daring things without making mistakes. "Some US presidents' wives--the 'First Ladies'--have been homey and down-to-earth. Mamie Eisenhower and Barbara Bush were like that. Others, such as Dolley Madison and Jackie Kennedy, have been sophisticated fashion leaders." In the field of engineering, it can means something very advanced and complicated, something that includes the very latest technology and yet works perfectly. "This phone is a present for my grandmother. I don't want anything too sophisticated. It just needs to be reliable and easy to use."