It says on page 3 (3rd bullet point) of this pdf document provided by IFAB that impeding the progress of an opponent with contact leads to DFK.
This video on the Laws of the Game which appears to be provided by FIFA states that an IFK is awarded if a player impedes the progress of an opponent, meanwhile the footage shows clear contact by the defender.
The video is much older than the IFAB document, so maybe the inconsistency is the result of recent amendments.
But I can't be sure, because another interpretation that comes to my mind is that the restart after an impeding offence depends on whether the nature of the contact in itself was the offence, or whether it was only the positioning of the offender from which contact naturally resulted and would not be considered part of the offence.