Market Structure is the structure of the market based on price either making higher lows and higher highs, making lower highs and lows, or making equal highs and equal lows. Market structure defines the condition of the market as trending, ranging or consolidating.
Price Action is the formation of candles on the chart and the way the candles are interacting with previous price action. Momentum, exhaustion, rejection, and indecision are price action characteristics.
Price Action and Market Structure are different components of chart analysis but have a strong relationship to each other. Within market structure we witness price action and within price action there is market structure due to the fractal nature of price.
Zig Zag (black line) shows Market Structure on top of the Price Action
From the zig zag illustration the market structure is obviously in a downtrend since it is making lower highs and lower lows. The price action also tends to reflect this as the bearish candles show the most momentum downwards and the most rejection upwards. Inside of this market structure there is supporting price action.
The path that price takes within price action is lower time frame market structure