Originally Posted by london
Whereas to me, polyamory means you agree to let your partner love others and directly opposes any restrictions on how you may love them.
And yet you see so many people posting here about how they're "allowed to be poly" so long as it's only with someone of the same sex or only if they don't [specific sexual act] in [specific geographical location] or only on alternate Tuesdays after approval from all existing partners and the production of STD test results in triplicate. They may be different rules, but they're still there for many relationships.
I would define "open" more as "anything goes" where there are very few rules to break. Both loving relationships and casual sex would fit in to that, but if it was a casual-sex-only, no-feelings-allowed type of thing I would categorise it as swinging rather than open.