Default placement type defines how the placement of new items should be handled.
• Pixel Placement – Items are placed using Left / Top pixels
• Relative Placement – Items are placed in relation to an item
Pixel placement has a small performance boost compared to relative placement so for max performance pixel placement should be used.
Relative placement has built in support for multiple different font-sizes and screen changes when SAP Business One is upgrade. For the best compatibility between SAP Business One versions/font-size Relative Placement should be used.
To learn more about the two different mode: See this video