Lightsail 3 Months Trial - Windows and Linux seperate?

The Lightsail 3-month free trial offer is separate for Windows and Linux instances, allowing you to take advantage of both simultaneously. You can run up to 750 hours per month of a Windows instance and 750 hours per month of a Linux instance during the trial period.

For Windows, you can choose from the $9.50/month, $14/month, or $22/month plans with IPv4 address, or the $8/month, $12/month, or $20/month plans with IPv6 address only, for free for 90 days.

For Linux/Unix, you can select from the $5/month, $7/month, or $12/month plans with IPv4 address, or the $3.50/month, $5/month, or $10/month plans with IPv6 address only, also free for 90 days.

This means you could potentially run one Windows instance and one Linux instance continuously (as 750 hours covers a full month) for the entire 3-month trial period without incurring charges, as long as you stay within the specified plan limits.

It's important to note that if you exceed the 750 hours per month for either the Windows or Linux instance, or if you choose a plan that's not included in the free trial offer, you will be charged for the excess usage or the non-eligible plan.
Sources
How many RDP i can create for free using Lightsail service? | AWS re:Post
Concerns about my Light Sail's 3 free months plan | AWS re:Post