SOQL (Salesforce Object Query Language) and SOSL (Salesforce Object Search Language) are powerful query languages used within the Salesforce platform to retrieve and manipulate data. They serve distinct purposes:

SOQL:

Purpose: Retrieves data from specific Salesforce objects (e.g., Accounts, Contacts, Opportunities).
Functionality:
Structured queries: Queries are based on object structures and field definitions.
Filtering: Allows for filtering records based on specific criteria.
Sorting: Enables sorting results in ascending or descending order.
Relationships: Can traverse relationships between objects to retrieve related data.
Aggregations: Performs calculations like SUM, COUNT, AVG on data.

SOSL:

Purpose: Performs full-text searches across multiple Salesforce objects and fields.
Functionality:
Text-based search: Searches for keywords or phrases within specified fields.
Cross-object search: Searches across multiple objects simultaneously.
Fuzzy matching: Supports approximate matches for misspelled or partially known terms.

Key Differences:

| Feature | SOQL | SOSL |
|---|---|---|
| Query Type | Structured queries on specific objects | Full-text search across multiple objects |
| Data Source | Specific objects and fields | Text fields in multiple objects |
| Matching | Exact or filtered matches | Keyword or phrase-based matching |
| Performance | Generally faster for specific queries | Can be slower for large datasets |

When to Use Which:

Use SOQL when:
You know the specific object and fields you want to query.
You need to filter, sort, or aggregate data.
You need to retrieve related data from other objects.
Use SOSL when:
You need to search for text across multiple objects.
You don't know the exact object or field containing the data.
You need to find approximate matches for search terms.

By effectively utilizing both SOQL and SOSL, Salesforce developers and administrators can efficiently retrieve and manipulate data to meet their specific needs.