What is the difference between shell-and-tube boilers and water-tube boilers?

(1) Water-tube boilers have a wide pressure range; they can overcome pressure limits and meet steam supply requirements of over 2.5 MPa. Fire-tube boilers are limited by the wall thickness of the materials and pressure, and are used at pressures below 2.5 MPa. (2) Fire-tube boilers are shell-type boilers; due to the limitations imposed by the equipment and tools available among current boiler manufacturers, it is difficult to construct fire-tube boilers of large size, with capacities usually being below 35 t/h. Boilers with a water-tube structure enable larger sizes; boilers of 35 t/h or more typically use this structure. (3) Fire-tube boilers feature a compact structure; at the same output, their size and weight are lower than those of fire-tube boilers. Boiler tubes boilers are larger in size, providing more space for the arrangement of superheaters; therefore, they occupy a relatively larger area in the boiler room

A shell-and-tube boiler is a fire-tube boiler, right?

A shell-and-tube boiler is generally a fire-tube boiler. For example, the WNS type.