Is Skype and Skype for Business the same or different ?

Are there differences between standard Skype and Skype for Business ? Is it possible to communicate between one user with Skype and other user with Skype for Business ? Is there a compatibility between both versions ?

There are some differences between Skype features and Skype for business features.

Skype is mostly dedicated for personal use or for smaller businesses.

Skype for business is more focused for business use in companies. It provides enterprise grade security and allows to add up to 250 users to online meetings at a time. You can also manage employee accounts. Users with Skype for business can communicate with users with Skype. It depends on admin settings. Is it also possible to choose to communicate only within the company. When external communications are not allowed, you will not see Skype users in the serach results.