OLTP: Online transactional transaction processing
It is characterized by large number of rows of data’s per second.
For each and every transaction of data will get store for time to time.
In OLTP database there is detailed and current data, and schema used to store transactional databases is the entity model (usually 3NF).
All the transaction in OLTP normally will consider as Normalized.
OLAP: Online Analytical Processing
It is characterized by very low volume of transactional data.
Normally OLAP will consider as De-normalized.
All the transactions are aggregated to view in very less rows of data.
In OLAP database there is aggregated, historical data, stored in multi-dimensional schemas (usually star schema).