What's the difference between Skype free and Skype for Business?
Skype for Business
Home, It is great for smaller businesses of up to 20 employees.
Business, provides enterprise grade-security, allows you to manage employee accounts.
Maximum number of users
Share photos, videos and files
Up to 300 MB
File storage and sharing with 1 TB of OneDrive storage
HD video calling
HD one to one or group video calling - now with call reactions