Tier pricing is a promotional tool that allows a store owner to price items differently for higher quantities.
"Stock quantity" is total quantity. It's reduced from when a shipment is shipped.
"Reserved qty" is product quantity that is ordered but not shipped yet.
"Planned qty" is product quantity that is ordered and already added to a shipment but not shipped yet.
The Related Products option provides the opportunity to advertise products that are not part of the selected category, to your visitors. These products are displayed on the product details pages.
The Cross-sell products option provides the opportunity to buy additional products that generally go with the selected product. They are displayed at the bottom of the checkout page.
Product attributes are quantifiable or descriptive aspects of a product (such as, color). For example, if you were to create an attribute for color, with the values of blue, green, yellow, and so on, you may want to apply this attribute to shirts, which you sell in various colors (you can adjust a price or weight for any of existing attribute values).
You can add attribute for your product using existing list of attributes, or if you need to create a new one go to Catalog > Attributes > Product attributes. Please notice that if you want to manage inventory by product attributes (e.g. 5 green shirts and 3 blue ones), then ensure that "Inventory method" is set to "Track inventory by product attributes".
Note that some attribute control types that support custom user input (e.g. file upload, textboxes, date picker) are useless with attribute combinations
Specification attributes are product features i.e, screen size, number of USB-ports, visible on product details page. Specification attributes can be used for filtering products on the category details page. Unlike product attributes, specification attributes are used for information purposes only.
Here you can see a list of orders in which this product was purchased.
Here you can see a history of the product stock quantity changes.