What's the difference between method and property(function)?

Question

What is the difference between fun1 and fun2 when define or runtime ?

const o = {
    fun1(param) {
        console.log("fun 1: " + param);
        return true;
    },

    fun2: (param) => {
        console.log("fun 2: " + param);
        return true;
    }
}