Common Lisp's condition system was first described in '83 for the Lisp Machine in a technical report that's hard to get one's hands on these days. It was described in an MIT AI Labs working paper a few years later by Pitman (https://dspace.mit.edu/handle/1721.1/41474).
The chief difference, IMO, is that Pitman defined terminology for a language feature in some LISP dialects, while Plotkin showed operational semantics for algebraic effects that are compatible with the denotational semantics (ie, adequacy). Pitman wrote his paper using the AI Labs' practical experience with LISP for the benefit of other LISP practitioners. Plotkin wrote his paper using previous work on lambda calculus and category theory for the benefit of programming language theorists.
Plotkin may have been unaware of CL's conditions system, but since conditions do not have formal semantics, and their behaviour is not particularly useful for probablistic non-determinism (the main thrust of Plotkin's effects article), I doubt that being aware of it would have made him any less motivated or likely to do the work he did.
Dolan et al (https://link.springer.com/chapter/10.1007/978-3-319-89719-6_...) discuss algebraic effects for concurrency in the setting of a dialect of OCaml, and reference CL conditions (amongst other things) as related work. It's a very brief mention observing only that conditions fail to convey the full continuation as a value to handlers, making them unsuited to the use case at hand.
TL;DR: no, conditions aren't the same thing, and if they were, they lack the rigour to be useful without the work that went into algebraic effects.
Algebraic effects were introduced by Plotkin in 2001 (https://link.springer.com/chapter/10.1007/3-540-45315-6_1) as an extension of Moggi's 1991 work on monads (https://www.sciencedirect.com/science/article/pii/0890540191...), which in turn built on work from the 70s and 80s on understanding computing from the perspective of category theory.
The chief difference, IMO, is that Pitman defined terminology for a language feature in some LISP dialects, while Plotkin showed operational semantics for algebraic effects that are compatible with the denotational semantics (ie, adequacy). Pitman wrote his paper using the AI Labs' practical experience with LISP for the benefit of other LISP practitioners. Plotkin wrote his paper using previous work on lambda calculus and category theory for the benefit of programming language theorists.
Plotkin may have been unaware of CL's conditions system, but since conditions do not have formal semantics, and their behaviour is not particularly useful for probablistic non-determinism (the main thrust of Plotkin's effects article), I doubt that being aware of it would have made him any less motivated or likely to do the work he did.
Dolan et al (https://link.springer.com/chapter/10.1007/978-3-319-89719-6_...) discuss algebraic effects for concurrency in the setting of a dialect of OCaml, and reference CL conditions (amongst other things) as related work. It's a very brief mention observing only that conditions fail to convey the full continuation as a value to handlers, making them unsuited to the use case at hand.
TL;DR: no, conditions aren't the same thing, and if they were, they lack the rigour to be useful without the work that went into algebraic effects.