The main difference between DataFrame and RDD in Apache Spark lies in their approach to data processing. DataFrames offer structured data processing capabilities, while RDDs handle unstructured data and provide more low-level control.

Implementing exponential backoff with jitter is a robust strategy for handling errors in a data pipeline. This approach gradually increases the time between retry attempts, reducing the load on the system during transient failures. Adding jitter introduces randomness to the retry intervals, preventing synchronization of retry attempts and reducing the likelihood of overwhelming the system when issues persist.

Fault tolerance plays a crucial role in real-time data processing systems by ensuring uninterrupted operation despite hardware or software failures. This is achieved through mechanisms such as replication, redundancy, and failover strategies. By maintaining system availability and data integrity, fault tolerance enables real-time systems to handle failures gracefully, minimizing downtime and ensuring reliable data processing.

Scalability is the ability of a real-time data processing system to handle high volumes of data with minimal delay. Scalable systems can efficiently process increasing data loads by distributing workloads across multiple resources or nodes, thereby maintaining performance and responsiveness. This is crucial for handling growing data volumes and maintaining system performance under varying workloads.

Parallelization is a technique used in ETL (Extract, Transform, Load) optimization to distribute data processing across multiple nodes or servers. It involves dividing the workload among multiple processors to improve efficiency and reduce processing time.

Change Data Capture (CDC) is a common technique in the ETL (Extract, Transform, Load) process. It captures changes made to data in the source systems and reflects them in the target system, ensuring data consistency.

Metadata management plays a vital role in facilitating data governance through data lineage by providing visibility into data origins and transformations. By documenting the flow of data from its source to its destination and capturing metadata about each step, organizations can understand how data is used, manipulated, and transformed across different processes. This visibility enables stakeholders to assess data quality, identify potential issues, and ensure compliance with regulatory requirements. Moreover, metadata management supports data lineage by linking data assets to business glossaries, policies, and standards, thereby enhancing data governance practices.

Outlier detection in data cleansing aims to identify and remove data points that deviate significantly from the rest of the dataset. Outliers can skew statistical analyses and machine learning models, leading to inaccurate results or biased predictions. Detecting and addressing outliers helps improve the quality and reliability of the dataset for downstream analysis and modeling tasks.

Strategies such as vertical and horizontal partitioning allow for distributing data across multiple resources, ensuring scalability by accommodating growing data volumes and supporting efficient data retrieval.

The DROP TABLE command is used in SQL to permanently remove a table and all its data from the database. It's important to exercise caution when using this command as it cannot be undone.