Standard, Miniature or Toy?

Poodles can come in a variety of sizes, distinguished by adult shoulder height.
FCI (Federation Cynologique Internationale) recognizes four sizes of one breed: Standard Poodle, Medium Poodle , Miniature Poodle and Toy Poodle. But non-FCI kenel clubs generally recognize three sizes - Standard, Miniature and Toy, sometimes as sizes of the same breed and sometimes as separate breeds.
The terms "royal standard", "teacup" and "tiny teacup" are marketing names and are not recognized by any major kennel club.

Some people might prefer a Standard Poodle, other might like a Toy.

A Toy can live for 13-15 years or longer. This Poodle can live very well in an apartment and he will lie next to you on the sofa but he also loves to play outdoors. Toys tend to develop Small Dog Syndrome, human induced behaviors where the dog believes he is the pack leader to humans. The dog is convinced he is the leader to humans. This little dog can be good with children, however is usually recommended for older children who know how to display leadership skills.

A Miniature Poodle tends to be dedicated to a single person and initially is shy with strangers. Some bark a lot, but they are good with other pets, children and dogs. The Miniature Poodle has a life span of 13 to 15 years. A Miniature can also develop Small Dog Syndrome - he needs rules and limits to what they are allowed to do.

A Standard is obedient, very good with children and has an adventurous spirit and will require more physical activities like swimming and retrieving. A Standard can live in an apartment but only if you give him a lot of outdoor exercise. Also standards can be effective guard dogs. A Standard lives for 10 to 13 years.

No matter what the size, a poodle is an intelligent and a friendly companion. All three sizes greet guests with a wagging tail, but they can also sound the alarm if a stranger is at the door. They are smart, responsive, eager to please and obedient.

Size
The Kennel Club (UK)
Australian National Kennel Council
New Zeeland Kennel Club

Canadian Kennel Club
American Kennel Club
United Kennel Club
Federation Cynologique Internationale
Standard
Over 38cm (15in)
38 cm (15 in) and over
38 cm (15 in) and over
38 cm (15 in) and over
38 cm (15 in) and over
38 cm (15 in) and over
Over 45 cm to 60 cm (+2cm) (18 to 24 in)
Medium
Not used
Not used
Not used
Not used
Not used
Not used
Over 35cm to 45cm (14 to 18 in)
Miniature
28 cm to 38 cm (11 to 15 in)
28 cm to 38 cm (11 to 15 in)
28 cm to 38 cm (11 to 15 in)
25.4 to 38 cm (over 10 in to under 15 in)
25.4 to 38 cm (over 10 in to under 15 in)
25.4 to 38 cm (over 10 in to under 15 in)
over 28 cm to 35 cm (11 to 14 in)
Toy
under 28 cm (11 in)
under 28 cm (11 in)
under 28 cm (11 in)
under 25.4 cm (10 in)
under 25.4 cm (10 in)
under 25.4 cm (10 in)
24-28cm (9.4 to 11 in)
Source: Wikipedia.org