Texture - A texture is an image that is used on a model to give the model details. UV maps tell the model which parts of a texture should use. There are many different types of textures, but the most common is the "Diffuse" texture, also known as the base colors.
Material - Different from a texture, a material is an asset that changes the appearance of the surface, materials can use many textures to achieve many different effects. Below you can see an example of a material in Unity using Poiyomi's Toon Shader.
Shader - In Unity, a shader is a program that contain instructions on how render materials. These are used in conjunction with materials. An example of a shader is Poiyomi's Toon Shader.
Screenspace Shader - Screenspace shaders can be used to make reflections, refractions, and make special effects. These should be used in heavy moderation when used for special effects as they can cause sickness or epilepsy in people.
Diffuse Map - A diffuse map is a type of texture that defines the color of an object.
Normal Map - Normal Maps are a type of texture to fake lighting bumps and dents on models. They can be identified by their distinct blue color, combined with cyan and pinks. Below is a 3 minute video explaining them further in detail.
Metallic Map - Metallic Maps are a type of texture used to define the areas that should behave like metal. Below is a short video quickly explaining how roughess maps work.
Roughness Map - Roughness maps are a type of texture that represents the smoothness/roughness of a surface. Below is a short video quickly explaining how roughess maps work.
Ambient Occlusion Map - An Ambient Occlusion map is a texture that contains shadow information. Below is a short video quickly explaining how ambient occlusionmaps work.
Masks - Masks are a type of texture you use to tell a material for example where a certain effect should be placed. These textures are grayscale. Often, the area you don't want to be affected should be black, and the area you do want to be affected should be white. These are greatly useful in a myriad of situations. Below is an example of a mask being used to tell the material to only apply the matcap to the bell of the model.
UV Maps - A UV Map, also just known as UVs, are a set of points that tells the model how to apply a texture. Below is comparison of a model and it's UV map, along with a sort of visualization that may help explain how UV mapping works.