Both OLTP and OLAP are databases but they have few differences. OLTP stands for Online Trasanaction Processing and OLAP stands for Online Analytical Processing.
1. OLTP is 2D databases i.e. a relational database where as OLAP is a multidimensional database i.e. a Cube.
2. If OLTP database is huge, then the performance becomes slow whereas OLAP database is super fast.
3. On a OLTP database, you can perform DML operations like Inserts, Updates, Deletes whereas on OLAP database, you usually select the data.
4. OLTP databases are the ones we create whereas OLAP databases are a result of SSAS solution.
Different OLTP databases like Oracle, MSSQL, MySQL etc become input for SSIS project which will result in a single large OLTP database. This output OLTP database contains historical data and is called as DataWarehouse which also becomes input for SSAS project which will result in a OLAP database known as a Cube. Both OLAP and OLTP databases can be input for a SSRS project to generate reports for the end users. The end user can also view reports directly from the output of SSAS solution without the need of SSRS reports such as Excel sheet to view the report.