Salesforce being the the world's #1 CRM has a number of security and identity features that allows you to secure your Org.
From an authentication & authorization perspective, there are two capabilities which can be used :
Salesforce Identity
Connected app framework
Both of these products are very good at what they do, but both of them are focused on securing access to Salesforce
Salesforce identity has a goal of securing user's access to your Salesforce Org or to the communities hosted by your Salesforce Org.
Connected apps allows you to grant access to your Salesforce Org for applications hosted outside of Salesforce (usually through API access).
Bringing your external ecosystem to Salesforce
CYM-Identity extends Salesforce Identity & the Connected App framework capabilities with a focus on :
Identity of applications which are not hosted on Salesforce
Identity for your APIs which are not hosted on Salesforce
Integration simplification & developer experience with a set of SDKs ready to be used
If your goal is to allow your employees or applications to use Salesforce and its APIs, or maybe you want to your partners or customers to use a Community, then you can use Salesforce Identity directly. CYM-Identity is not made for this.