Photoshop provides a variety of effects—such as shadows, glows, and bevels—that change the appearance of a layer’s contents in a non-distructive way. Layer effects are linked to the layer contents. When you move or edit the contents of the layer, the same effects are applied to the modified contents. For example, if you apply a drop shadow to a text layer and then add new text, the shadow is added automatically to the new text.
A layer style is one or more effects applied to a layer or layer group. You can apply one of the preset styles provided with Photoshop or create a custom style using the Layer Style dialog box. The layer effects icon appears to the right of the layer’s name in the Layers panel. You can expand the style in the Layers panel to view or edit the effects that compose the style.
You can apply multiple effects in a single layer style. Also, more than one instance of some effects can comprise a layer style.