Difference between Compact Layout and Page Layout ?

Hello Saloni gupta,

Compact Layouts :

Compact layouts display a record’s key fields at a glance in both Salesforce1 and Lightning Experience.
In the full Salesforce site, a compact layout determines which fields appear in the Chatter feed item that appears after a user creates a record with a quick action.
In Salesforce1, the first four fields that you assign to a compact layout appear in:
An object’s record highlights area
Expanded lookup cards on a record’s related information page
In Lightning Experience, the first five fields that you add to a compact layout display in an object’s record highlights panel and in the expanded lookup card you see when you hover over a link in record details.
Page Layouts :

Page layouts control the layout and organization of buttons, fields, s-controls, Visualforce, custom links, and related lists on object record pages. They also help determine which fields are visible, read only, and required. Use page layouts to customize the content of record pages for your users.
Page layouts can include s-controls and Visualforce pages that are rendered within a field section when the page displays. You can control the size of the s-controls and Visualforce pages, and determine whether or not a label and scroll bars display.
Salesforce has two drag-and-drop tools for editing page layouts: the original page layout editor and an enhanced page layout editor. The enhanced page layout editor is enabled by default, and provides all the functionality of the original editor, as well as additional functionality and an easier-to-use WYSIWYG interface.
You can enable the original page layout editor in the User Interface settings. Your Salesforce org can use only one page layout editor at a time.
From within a page layout, you can access a mini page layout. The mini page layout defines the hover details that display when you mouse over a field on an object’s detail page in the Agent console or in the Recent Items section of the sidebar in Salesforce Classic.