re: Question - wall construction materials

Several years ago had a hot water heater leak and had to add an access panel. Handyman was shocked when he was trying to cut through the sheetrock. There is 3/4" tongue & groove in all of my walls. When he cut into it the pine smelled like it had just been milled. Is this considered ship lap? Family home built in 1963. Dad owned a lumberyard so not surprised he built it so well.

Thanks, I had seen older homes where thinner slats were in the walls (for plastered walls maybe) and referred to as ship lap. Was not sure if the term applied to both types. Now when I have work done I can at least refer to it with the proper terminology!
Again, thanks for the clarification.