Baryons are heavy hadrons; they are fermions with spin $$\dfrac{1}{2},\dfrac{3}{2},\dfrac{5}{2},...;$$ well they are composed of three quarks. (Antibaryons are composed of three antiquarks.) Mesons are light hadrons; they are bosons with spin $$0, 1, 2, ...;$$ they are composed of a quark and an antiquark.