Group therapy is frequently assumed to be individual therapy made cheaper. The mechanisms it uses are different, and for some difficulties they are the point.
Other people supply information a therapist cannot
In individual sessions, a person describes interactions from memory, and the account is necessarily shaped by how she experienced them.
A group provides interactions happening in the room, observable by everyone present, so patterns in how someone relates to others can be examined as they occur rather than reconstructed.
That is why groups are often used for difficulties that are fundamentally interpersonal, where the material only exists when other people are present.
Universality does work that reassurance cannot
Hearing a clinician say that a feeling is common is information. Hearing several peers describe the same experience unprompted is evidence, and it lands differently.
Adolescents in particular weight peer testimony heavily, which makes the format well matched to that stage even when adults find it counterintuitive.
The effect works in both directions, since being the person whose account helps someone else changes a participant's sense of what she has to offer.
Structure varies more than people expect
Some groups follow a defined curriculum with skills taught in sequence across a set number of sessions. Others are open-ended and process-oriented with no set content.
These are genuinely different treatments with different aims, and knowing which is being offered matters more than the general label of group therapy.
Size, whether the membership is fixed or rotating, and whether participants are grouped by age or by difficulty all change the experience substantially as well.
Confidentiality operates differently
A clinician is bound by professional and legal obligations. Other participants are bound by an agreement, which is meaningful and is not the same as a legal duty.
Groups address this explicitly at the outset, and anyone considering one should ask how it is handled, particularly in a setting where members attend the same school.
That overlap is common in school-based and small-community groups, and it is a reasonable thing to raise with the facilitator before joining rather than after.
Fit is a clinical judgment, not a preference
Group formats are not appropriate for every person or every stage, and acute crisis, certain trauma presentations and some conditions are usually addressed individually first.
That determination belongs to a qualified mental health professional who can assess the individual, and nothing about the format's mechanisms substitutes for that assessment.
Where both are available, they are frequently combined rather than chosen between, with individual work and group work addressing different parts of the same difficulty.