Question on lumber, pine vs whiteboard?

[Rita B.]

While purchasing lumber for a project that will be painted,  the big box store sales lumber in pine and whiteboard.   The pine is more expensive and heavier in weight with less knots.  The whiteboard is easier on the budget, lighter weight with more knots.    Google search describes the two as a yellow pine and white pine and the store guy just sort of shrugged and told me there was no difference except for the price.   So that leaves me with the question of the structural integrity.  Any difference other than appearance and cost?

[Marc Sadovnic]

Thanks David and Rita B.  I get it now.

Marc

[Orvel Johnson]

I needed an extra long threshold to transition between carpet and vinyl flooring, and went to Lowe's.  They didn't have anything long enough, and I didn't want to use pine (too soft).  I asked an associate if they had any oak, and he gave me (and my appearance) a once-over.  He said they did carry oak, but it was very pricey.  I had a good laugh.  I found several widths and lengths, and was able to use my table saw to undercut for the transition height.   Then I used my router to smooth the edges.