Since you posted the speedtest.net images and the host server is the same, I will rule out factors at the speedtest.net side.
This leaves me with a few ideas as to why this is happening.
Firstly, on the ISP side:
- It is not unusual to see extra few megabits over your assigned Internet plan, especially if your contract is a business contract or your ISP is a high quality and reputable one. That is being said, only a few megabits of extra speed are common here.
- Some ISPs on the other hand apply a short speed burst for a few seconds at the beginning of each connection. This can report false speeds since speedtest.net tests only last for a few seconds.
- Some other ISPs have variable speeds limits for different hosts or websites for example the ISP's hosts and website may download at higher speeds.
Short answer here: This applies exactly the same to connected machines at your side, regardless of their operating systems.
Secondly, on your side:
- Windows operating system has power management by default set to optimized performance which tries to balance power consumption with performance and this may affect different aspects of your hardware and software which results sometimes in reduced connection speeds. To test if this is the cause of the difference in speed you see, you could try setting Windows power management to high performance and test again.
- Windows operating system has built in firewall and antivirus enabled by default. They curry on checks in the back-ground which ,depending on the settings, may significantly interfere with and slow down file transfers of any kind. To test if this is affecting your download speed, ( although not recommended ) you could try disabling the firewall and antivirus and test again.
Suggestions for more accurate measuring mechanisms:
speedtest-cli command line tool on Ubuntu to rule out browser-side factors:
Install it by running
sudo apt install speedtest-cli in the terminal.
Use it by running
speedtest-cli in the terminal.
For windows you can try the app from speedtest.net.
Download a large file from a fast server and time the download. To calculate your speed in Mbit/sec divide the file size in MB by the time in seconds then multiply by eight (size in MB ÷ time in seconds) × 8.
Your internet speed is determined by your ISP NOT by your operating system. It is not possible to get higher speeds than the one assigned to you by your ISP by any means known until now.