map = {} vs map = new Map() in javascript

I am studying algo & ds. And there are many times we use the map. For example, Leetcode 1 problem, two Sum. We can solve it as below.

var twoSum = function(nums, target) {
    let map = new Map();
    
    for (let i = 0; i < nums.length; i ++) {
        if (map[nums[i]] >= 0) {
            return [map[nums[i]], i]
        }
        map[target-nums[i]] = i
    }
    return [-1, -1];
};

But I am not sure what's the difference between

let map = {};

and

let map = new Map();

Please enlighten me.

Thank you.