Read depth is the sum of the mapped read depths at each reference base position, divided by the number of known bases in the reference. While coverage is the number of unique reads that include a given nucleotide in the reconstructed sequence.

This picture will make you clear about the read depth and coverage in NGS

Dear Arad Boustan . See the following useful link: https://www.nature.com/articles/nrg3642

Kindly see also the following useful link: https://support.illumina.com/bulletins/2017/04/considerations-for-rna-seq-read-length-and-coverage-.html

Also check please the following useful RG link: Article RNA Sequencing and Analysis

The following RG link is also very useful : Article Evaluating the Impact of Sequencing Depth on Transcriptome P...

Visit kindly the following useful link: https://www.frontiersin.org/articles/10.3389/fgene.2020.562445/full

Dear Aref and Dear Shahina

Thank you for providing these links.

Sequencing coverage or depth (coverage and depth are used interchangeably) determines the number of times sequenced nucleotide bases covered the target genome. The breadth of coverage refers to the percentage of genome bases sequenced at a given sequencing depth. Read more here https://www.reneshbedre.com/blog/sequencing-coverage.html