Cyanobacteria vs. Algae — What's the Difference?

Cyanobacteria , also known as Cyanophyta, are a phylum of Gram-negative bacteria that obtain energy via photosynthesis. The name cyanobacteria comes from their color (Greek: κυανός, romanized: kyanós, lit. 'blue'), giving them their other name, "blue-green algae", though modern botanists restrict the term algae to eukaryotes and do not apply it to cyanobacteria, which are prokaryotes.

Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades.

Any of various photosynthetic bacteria of the phylum Cyanobacteria that are generally blue-green in color and are widespread in marine and freshwater environments, with some species capable of nitrogen fixation. Also called blue-green alga, blue-green bacterium.

Any of numerous photosynthetic organisms of aquatic or moist habitats, ranging in size from single-celled diatoms to large seaweeds such as kelp, and characterized by a lack of complex organs and tissues. Once classified within the plant kingdom, the algae are now considered to include several unrelated groups belonging to different kingdoms.

Plural of cyanobacterium.

Algal organisms viewed collectively or as a mass; algal growth.

Predominantly photosynthetic prokaryotic organisms containing a blue pigment in addition to chlorophyll; occur singly or in colonies in diverse habitats; important as phytoplankton

(countable) A particular kind of algae.

Plural of alga.

Primitive chlorophyll-containing mainly aquatic eukaryotic organisms lacking true stems and roots and leaves