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 illustration above 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
The illustration above shows the fractal nature of the market and the close relationship between price action and market structure. Both are within each other. The sum of all the price action creates market structure and within price action there is fractal market structure on a lower time frame. No matter how low of a time frame you view there will be price action inside of market structure that is inside of price action that is inside of market structure and so on and so on, infinitely.
You can't have market structure without price action and you can't have price action without market structure.
Price action is more than just momentum, rejection, and indecision candles. Price action is formation of price on the time frame that you are currently looking at as well as the market structure of the lower time frames.
The market structure that you see on your chart contains price action but it is also the fractal market structure within a higher time frame's price action.
Market Structure and Price Action are inseparable twins that both share the throne as being king.