Tartan' - the pattern and 'Plaid' - a blanket & not a design

Tartan or plaid are they the same thing ? The answer is no.

• 'Tartan' is the actual pattern of cloth the garment is made from.
•  Originally, tartans were made from woven wool. Up until the mid-19th century, Highland tartans were linked more to specific regions than to clans. This was because local weavers created designs tailored to the preferences of their communities, often utilizing natural dyes available in their area. Over time, tartans became closely associated with Scottish clans and families 
• .Originally, tartan didn’t need a pattern and could be plain-colored. In the 1830s, patterned cloth from the Gaelic Highlands was called "breacan," meaning "many colors." Over time, "tartan" and "breacan" merged to describe patterned cloth. A tartan’s pattern, called a "sett," is created by threads crossing at right angles.
• 'Plaide' comes from the Gaelic word for "large wrap" or "blanket," also called "The Belted Plaid" (feilidh-mhor). It’s a blanket gathered and belted at the waist. Tartan refers to the cloth's pattern, while plaid is the garment made from it.