What is the difference between test bed and test data?

Test Bed consist of test data and other hardware components i.e. its a bigger
picture than only software data
Test Data are data which have been specifically identified for use in executing
test scripts, ( They may form a subset of test bed)

Test Bed:
Preparation for test execution is called Test Bed, i.e., installing your application (including pre-requisites like IE 6.0, .Net 2.0, IIS, Oracle, creating Windows User with Administrator rights etc), preparing database/schema.
That means making sure that the application is READY for test execution.

Test Data:
On the other hand, test data is the data which is being used in the test execution (Eg, Input needs to be entered while creating a New User, First Name, Last Name, Age, Address, Sex, and Phone Number etc comes under test data

Test Data are data which have been specifically identified for use in executing test scripts, and are used to verify the expected results obtained.

Ex: Let us consider I have a login screen which I want to automate, parameterize
and run 10 iteration, so I have to prepare a set of data of all user id and password before
I go for automation to get the expected results. This is call preparation of test data.

Test Bed or Test Environment is setting up of the both hardware and software requirements

Ex: Assume I have a PDA or handheld device or mobile, I have developed software which can change a format of a song from any format to mp4. After me converting the song, I will get a list of mp4 files as an xml file. I can transfer this file from the computer to the handheld device using USB cable.

Now for checking this entire scenario, I have to set up my software environment( data) and also need to setup my hardware ( which is my PDA and my USB connected to my computer).