Google Sheets is free, fully integrated into Google's ecosystem, instant to load a use, seamlessly integrated into web browsers without requiring any downloads.
Available on mostly every smart device, phone, tablet and computer.
Sheets is a fully featured software, it allows from very basic calculations, or just simple table arrays and displays to more advanced math operations. You can use it from anything from a very basic table you just want to display, to advanced company data management full of thousands of data entries with advanced formulas performing calculations.
Sheets is seamlessly integrated into the google ecosystem to the point of instant and easy collaboration. It allows you to set permits and collaborate with friends, coworkers and anyone you choose, while deeply customizing their available options and permits.
Sheets is available on pretty much any smart platform or computer allowing you to always have your documents ready for viewing or editting.
Excel dominates the market, and Google sheets loses some of that functionality, advanced formulas and macros that excel uses.
You may lose important formatting or operations when moving between them, forcing you to stick to only one platform.