An inside bar is a two-candle pattern where the second sits inside the first's range, while a pin bar is a single candle with a long wick signaling rejection. A pin bar is a single candlestick pattern with a long wick and a small body that signals rejection of price levels, while an inside bar is a two-candle pattern where the second candle is contained within the range of the first candle, indicating consolidation before a breakout.
Inside bars indicate a pause before a breakout in either direction; pin bars indicate a sharp turn at a specific level.