(group of stars apparently formed by a single cloud)
A stellar cluster or star cluster (sometimes abbreviated SC)
is a general term
including both globular clusters and open clusters,
consisting of groups of stars near each other,
with other similarities that suggest their formation is from a
single cloud.
The distinction between globular versus open clusters is that
the former are tightly bound by gravity and the latter
is more loosely bound.
A young stellar cluster (YSC) is one showing signs of being
young, i.e., ultraviolet indicating early stars.
In surveys for finding stellar clusters,
possible YSCs have been
termed YSCCs for young stellar cluster candidates.
An embedded cluster (EC) is a cluster within a gas cloud,
i.e., one still residing in the cloud of its formation.
A stellar association is looser than an open cluster but shows
signs of common origin, such as similar age and metallicity.
Often it is a moving group (aka kinematic group), a group
of stars that are generally moving together. Such groups are
presumed to be the remnants of stellar clusters, a notion supported
by the fact that such groups often show older stars than typical
of open clusters.
The term galactic cluster (as opposed to galaxy cluster, a
gathering of galaxies) is used for stellar clusters,
particularly those within the Milky Way.