Here's how you can get the comprehensive full fledge difference of two dates.
function diffYMDHMS(date1, date2) {
let years = date1.diff(date2, 'year');
date2.add(years, 'years');
let months = date1.diff(date2, 'months');
date2.add(months, 'months');
let days = date1.diff(date2, 'days');
date2.add(days, 'days');
let hours = date1.diff(date2, 'hours');
date2.add(hours, 'hours');
let minutes = date1.diff(date2, 'minutes');
date2.add(minutes, 'minutes');
let seconds = date1.diff(date2, 'seconds');
console.log(years + ' years ' + months + ' months ' + days + ' days ' + hours + '
hours ' + minutes + ' minutes ' + seconds + ' seconds');
return { years, months, days, hours, minutes, seconds};
}