All these three site are most famous and reliable site for freelancing. I will show you the main differences here through these two table.
In this table you can understand easily about how much designer are on site, how many live projects on sites now, commission fee, winning changes etc.
In this second table you can see all these site are Australia based company and stated the almost the same year as per Wikipedia. I work all of them and win the project each site.
you can see more on each site on my youtube channel https://youtube.com/c/kasturilal
To understand in hindi watch this video.