What are the differences between DNA and RNA sequencing?

Massive parallel DNA sequencing (synonyms are: DNA deep sequencing | DNA high-throughput sequencing | DNA-seq) includes Whole Genome Sequencing (WGS), Whole Exome Sequencing (WES or WXS) and targeted sequencing. WGS implies sequencing of the entire DNA genome, while WES focuses on sequencing only mRNA coding regions (exons) which usually represent a very minor genome fraction (3% in humans).  While both WGS and WES are used to discover rare mutations and/or common variants associated with a disorder or phenotype, WES is significantly less expensive and faster than WGS. Targeted sequencing focuses on only a subset of genes (or DNA regions) of interest and is the fastest and cheapest DNA-seq type.

Massive parallel RNA sequencing (synonyms are: RNA deep sequencing | RNA high-throughput sequencing | RNA-seq) includes Whole Transcriptome Sequencing (WTS), mRNA sequencing (mRNA-seq) and small RNA sequencing (smRNA-seq). Unlike DNA-seq, RNA-seq requires extracted RNA to be first reverse-transcribed into cDNA and then amplified. Most common applications of RNA sequencing are the detection of changes in gene expression, alternative splicing, post-transcriptional modifications, gene fusions as well as detection of mutations and SNPs.

Reference: 

https://sciberg.com/resources/bioinformatics-faqs/the-differences-between-dna-and-rna-sequencing.html#:~:text=Unlike%20DNA%2Dseq%2C%20RNA%2D,detection%20of%20mutations%20and%20SNPs.