Both desmosomes and tight junctions are clusters of proteins that act by binding membranes of adjacent cells. However, they have some differences. While desmosomes cross the plasma membrane and thus provide a stronger bond, the tight junction proteins (claudins) remain on the outside of the membrane and bind to the claudins of other cells; therefore, they provide a less strong binding than desmosomes, but function to make the tissue impermeable. The bladder is an organ that possesses many tight junctions.
In conclusion:
Similarities:
1- They bind cell membranes
2- They are composed of proteins
Differences:
1- Desmosomes go through the membrane, tight junctions do not.
2- Desmosomes are a stronger junction that holds the tissues together.
Tight junctions are less strong and their main function is to maintain an impermeable barrier.