Sandboxes in Salesforce

This is copy of your organization in a separate environment which can be used for testing, training, development etc.. 

These are completely isolated from your production or live organization that is the operations you perform in your sandboxes don’t affect your Salesforce production organization. 

Types:

Developer Sandbox

Features:

• Refresh Interval is 1 day
• Storage Limit is Data storage: 200 MB, File storage: 200 MB,
• Copies Metadata only
• Sandbox templates are not available

Developer Pro Sandbox

Features:

• Refresh Interval is 1 day
• Storage Limit is Data storage: 1 GB, File storage: 1 GB,
• Copies Metadata only
• Sandbox templates are not available

Partial Copy Sandbox

Features:

• Refresh Interval is 5 day
• Storage Limit is Data storage: 5 GB, File storage: Same as your production org,
• Copies Metadata and sample data
• Sandbox templates is Required

Full Sandbox

Features:

• Refresh Interval is 29 day
• Storage Limit is Same as your production org
• Copies Metadata and all data
• Sandbox templates are Available

Reference:

https://help.salesforce.com/s/articleView?id=sf.create_test_instance.htm&type=5

https://help.salesforce.com/s/articleView?id=sf.data_sandbox_templates.htm&type=5