What's the difference between these? [duplicate]

This question already has an answer here:

• What's the difference between & and && in JavaScript? 4 answers
• What is the correct Javascript operator precedence table? 2 answers

i'm creating a small table game and it was always buggy so tried changing some stuff. And now it somehow works. I just don't know how this changed anything?

if((board1_1 && board2_1) == 1){..}

if((board1_1 & board2_1) == 1){..}

if(board1_1 && board2_1 == 1){..}

if(board1_1 & board2_1 == 1){..}