You know, they say laughter is the best medicine.
Assuming dnd 5e, obligatory mention that the caster is not supposed to choose what gets summoned with summoning spells. The caster picks a category ("8 creatures with CR etc etc"), and the GM determines what is summoned ("the GM has the creatures’ statistics").

Beastmaster ranger

You magically summon a primal beast, which draws strength from your bond with nature. Choose its stat block: Beast of the Land, Beast of the Sea, or Beast of the Sky. You also determine the kind of animal it is, choosing a kind appropriate for the stat block. Whatever beast you choose, it bears primal markings indicating its supernatural origin.

Druid familiar summon

You gain the service of a familiar, a spirit that takes an animal form you choose: Bat, Cat, Frog, Hawk, Lizard, Octopus, Owl, Rat, Raven, Spider, Weasel, or another Beast that has a Challenge Rating of 0. Appearing in an unoccupied space within range, the familiar has the statistics of the chosen form, though it is a Celestial, Fey, or Fiend (your choice) instead of a Beast. Your familiar acts independently of you, but it obeys your commands.

Summon beast

You call forth a bestial spirit. It manifests in an unoccupied space that you can see within range and uses the Bestial Spirit stat block. When you cast the spell, choose an environment: Air, Land, or Water. The creature resembles an animal of your choice that is native to the chosen environment, which determines certain details in its stat block. The creature disappears when it drops to 0 Hit Points or when the spell ends.

It looks like it’s for stuff like summon lesser demons, conjure animals, conjure woodland beings, conjure fey, planar ally, and conjure celestial