# Understanding Orders & Shipments

In ShipStation API v2, what you might think of as an "order" is actually called a **shipment**. This terminology shift can be confusing if you're coming from the ShipStation UI or the v1 Companion API, but it aligns with industry-standard shipping terminology.

## Core Concepts

### What is a Shipment in v2?

A **shipment** in v2 represents the intent to ship something. It contains:

- Ship-to and ship-from addresses
- Package dimensions and weight
- Items being shipped
- Carrier and service preferences
- Custom metadata and identifiers


In the ShipStation UI and v1 API, this same concept was called an **order**.

### What is a Label in v2?

A **label** in v2 represents a purchased shipping label from a carrier. It includes:

- The actual label file (PDF, PNG, ZPL)
- Tracking number
- Shipping cost
- Carrier details
- Associated shipment information


In the ShipStation UI and v1 API, this was called a **shipment**.

## Quick Reference Table

| **ShipStation UI / v1 Term** | **v2 API Term** | **What It Represents** |
|  --- | --- | --- |
| Order | Shipment | Intent to ship; order details and addresses |
| order_id | shipment_id | Unique identifier for the shipment (with `se-` prefix) |
| orderNumber | shipment_number | User-friendly reference number |
| orderKey | external_shipment_id | Your system's identifier for the shipment |
| Shipment | Label | Purchased shipping label from carrier |
| shipment_id | label_id | Unique identifier for the label (with `se-` prefix) |


## Why the Terminology Changed

The v2 terminology aligns with how most shipping carriers and APIs describe these concepts:

- **Shipment** = The shipping request/intent (what you're sending and where)
- **Label** = The physical/digital artifact used to ship it


This makes integration more intuitive for developers familiar with carrier APIs like UPS, FedEx, and USPS, and matches the terminology used by ShipEngine API.

## Related Guides

For detailed information about specific aspects of orders and shipments in v2:

- **[External Identifiers Guide](/orders/external-identifiers)** - Learn about `external_shipment_id`, `external_order_id`, and how they relate to v1 `orderKey`
- **[Shipment Numbers & Uniqueness](/orders/shipment-numbers)** - Understand `shipment_number` uniqueness rules and auto-population
- **[Legacy API Migration](/orders/legacy-migration)** - Migration guidance for v1 users and legacy ShipStation UI behavior
- **[Products and Plans - Terminology Reference](/products-and-plans#api-version-terminology-reference)** - Complete v1 to v2 terminology mapping