Type 1 is where an existing telephone line is used for both ADSL data communication and voice calls. In fact, both ADSL data communication and voice calls can be made at the same time on the same line.
Type 2 is where a new line is supplied for ADSL data communication only. Voice calls through the telephone network cannot be made on a Type 2 line. Type 2 may need a new installation of ADSL line. In that case, you may be requested to be present at the installation.