Flandry: seven stories, collected in two volumes.
Okies: four stories, collected in one volume; Okie civilisation ends in the third so the fourth is an aftermath.
Works Written Later But Set Earlier
Flandry: three "Young Flandry" novels.
Okies: one prequel and one juvenile novel.
Works Set Later
Flandry: two later Flandry novels; one novel about his daughter; four works set after the Empire = one novel + one collection(?)
Okies: one novel about the end of the universe.
Flandry: the earlier Technic History.
Okies: other series with related ideas.
Qualitatively though not quantitatively comparable.