Concise answer
A keloid grows beyond the boundaries of the original injury, while a hypertrophic scar remains raised within them. Appearance alone may be difficult to judge, especially early in healing.
Both can be itchy, tender or firm and may behave differently depending on body location and individual scarring tendency.
Cutting, burning or applying strong acids at home can worsen a raised scar.
When evaluation may help
Seek assessment when a scar is growing, painful, persistently itchy or extending beyond the original wound before any cosmetic procedure is attempted.