Is there a difference between the universe and the cosmos? I used to think that the cosmos was a sort of container for the universe, one that could contain potentially infinite universes.
In technical (astrophysics) usage no.
There are a number of different uses of universe but cosmos isn't used as a specific technical term. Cosmos is sometimes used in popular works as a homage to Carl Sagan's famous TV series.
Cosmological is used as a technical term, eg. Cosmological constant, Cosmological redshift - because using "Universal" would be confusing.
Universe means "the whole world" or "all taken collectively".
While Cosmos comes from the Greek Kosmos (from the OED: κόσµος - order, ornament, world or universe (so called by Pythagoras or his disciples ‘from its perfect order and arrangement’).
Cosmos is the opposite of Chaos, which was the first state of the universe.
Nowadays they are used like synonyms; they refer to the same thing, but seen from different "point of views".
Yes, there is a difference.
Cosmos refers to the order found within the universe.
It is the opposite of Chaos, which refers to the disorder found within the Universe.
Carl Sagan is a tribute to the human race, here is one description he gave in the TV show Cosmos. "Cosmos is a Greek word for the order of the universe. It is, in a way, the opposite of Chaos. It implies the deep interconnectedness of all things. It conveys awe for the intricate and subtle way in which the universe is put together."
The word universe should be interpreted as "our Universe", i.e. the universe we live in that originated with the Big Bang that occured about 13.7 billion years ago and is currently estimated to be commprised of between 100 and 400 billion galaxies. Our Universe is currently expanding and will continue to expand for many billion years; however, ultimately it will begin to contract and will contract for many additional billion years. Most of our Universe will be consumed in a Monster Black Hole that will develop near the center of our universe. The Monster Black Hole will at some point explode in another Big Bang that will be the end of our Universe and the birth of our successor universe. A relatively few galaxies will heading toward the Monster Black Hole at speeds much greater than the speed of light when the Big Bang occurs and these galaxies will provide the inflation perion of our successor universe. Our Universe is only a small part of the cosmos which is everthing that exists, has existed and will exist and includes previous universes, parallel universes and future universes.