What is the difference between Streptococci and Staphylococci?

Hint: Streptococci are a type of gram-positive bacteria. They belong to the family Streptococcaceae.
Staphylococci are a type of gram-positive bacteria. They belong to the family Staphylococcaceae.

Complete answer:
Streptococci belong to the order of Lactobacillales and are a part of the phylum Firmicutes. Streptococci are cocci or spherical-shaped bacteria. Streptococci tend to form long chains or pairs during cell division. These chains or pairs appear to be twisted or bent. Streptococci bacteria are mostly oxidase-negative and catalase-negative. Many Streptococci bacteria are facultative anaerobic bacteria i.e they can grow in both aerobic and anaerobic environments. Streptococcus bacteria are pathogenic and cause diseases like, Strep throat, Pink eye, Meningitis and bacterial pneumonia.
Staphylococci are a part of the order of Bacillalles and belong to the phylum of Firmicutes. Staphylococci are structurally spherical bacteria and form grape-like structures. These grape-like clusters are formed due to the division of the bacteria along multiple axes which generates these irregular, grape-like structures. Staphylococcus bacteria can propagate in both aerobic and anaerobic environments. Hence, they are called facultative anaerobic bacteria. Most of the species of the genus Staphylococcus are non-pathogenic and are found on the skin and mucous membranes of humans and several animals.

Note:
There are over 50 recognized species of Streptococci. Streptococci bacteria are mostly found in the salivary microbiome.
The genus of Staphylococcus includes at least 40 species of bacteria. Nine bacteria in the genus of Staphylococcus have two subspecies, one bacterial species has three subspecies and one bacterial species has four subspecies.