Difference Between Sigma & Lambda Baryons

[barrinmw]

While doing my homework for physics, we are doing what quarks make up different baryons and such and I can across something I don't understand, what is the difference between a neutral sigma baryon and a neutral lambda baryon? They both have an up down and strange quark combination and the sigma decays into the lambda with the release of a gamma, so why is it considered a separate particle? Shouldn't a neutral sigma be considered an excited neutral lambda?

 

[Vanadium 50]

They have different wavefunctions, and so are different particles.