What type of Op Amp or comparator has a schematic symbol with hysteresis like symbol
The second block in your schematic is clearly a inverter with Schmitt trigger input.  Since the first block was presumably drawn by the same person, I think they are trying to point out that it does NOT exhibit hysteresis, in contrast to the second block.  That's a guess, but I think makes sense.  Usually one doesn't draw anything special to indicate a block has a normal "linear" response.