In Power Apps, the search, lookup, and filter functions serve different purposes:

Lookup:

The Lookup function is used to retrieve a specific record from a data source based on a matching value in a specific column. It is commonly used to retrieve a single value from a related table or list. The syntax for the Lookup function is:

Lookup(datasource, column, value)
For example, the following formula retrieves the email address for an employee with the ID “1122” from a SharePoint list called “Employees”:

Lookup(Employees, “ID”, “1122”, “Email”)

Search:

The Search function is used to find records in a data source that match a specific set of criteria. It allows you to search across multiple columns of a table or a collection for a specific value or set of values. The syntax for the Search function is:

Search(datasource, searchstring, column1, column2, …, columnN)
For example, the following formula searches for records in a SharePoint list called “Employees” that contain the text “Anish” in either the “First Name” or “Last Name” column:

Search(Employees, “Anish”, “First Name”, “Last Name”)

Filter:

The Filter function is used to retrieve a subset of records from a data source based on a set of criteria. It allows you to filter a table or a collection based on one or more conditions. The syntax for the Filter function is:

Filter(datasource, condition1 && condition2 && … && conditionN)
For example, the following formula retrieves all records from a SharePoint list called “Employees” where the department is “Marketing” and the location is “India”:

Filter(Employees, Department = “Marketing” && Location = “India”)

Note:-

The Search function is used to find records based on a specific text string

Lookup function is used to retrieve a specific record based on a matching value in a specific column

Filter function is used to retrieve a subset of records based on a set of conditions.