arrow vs function declaration

fn.ts

const Module = {
  value: 0,
  someFn: () => {
    return this.value;
  },
  okayFn() {
    return this.value;
  }
}
class Module2 {
  value = 0;
  someFn = () => {
    return this.value;
  }
  okayFn() {
    return this.value;
  }
}

console.log(
  {
    ModuleValues:
      {
        someFn: Module.someFn(),
        okayFn: (Module.add(),Module.okayFn()),
      },
    Module2Values:
      {
        someFn: new Module2().someFn(),
        okayFn: new Module2().okayFn(),
      }
  }
)
It returns //
/*
{
    "ModuleValues": {
        "someFn": null,
        "okayFn": 0
    },
    "Module2Values": {
        "someFn": 0,
        "okayFn": 1
    }
}
*/