The difference between supply zones and order blocks lies mainly in their origin, precision, and how traders interpret institutional activity. A supply zone is a broader price area where selling pressure has previously exceeded buying pressure, causing the price to drop. It is typically identified by observing sharp declines or consolidation followed by a strong bearish move. Traders use supply zones to anticipate potential reversals or selling opportunities when the price revisits that area.

On the other hand, an order block is a more refined and specific concept rooted in smart money theory. It represents the last bullish candle before a strong bearish move (for a bearish order block) or the last bearish candle before a strong bullish move (for a bullish order block). Order blocks are believed to indicate where institutional traders, such as banks, have placed large orders, making them more precise entry points.

Another key difference is accuracy. Supply zones are often drawn as wider regions, while order blocks are narrower and focus on specific candles, allowing for tighter stop losses and better risk management. Additionally, order blocks are usually confirmed by market structure shifts like break of structure (BOS), whereas supply zones rely more on general price behaviour.

In summary, supply zones highlight general areas of selling interest, while order blocks pinpoint exact levels where institutional activity likely occurred, offering more precision for advanced traders.