There are also size differences with wide radius track between brands as respects to O27 height track.
This is from my website's blog post entitled "Lionel Tubular Track Info and Tips":
"When using O27 height wider radius track, even small differences can leave one scratching their head when things just don't seem to line up.
When using O54 curve track please note that the K-line version is 1/4 inch longer than Lionel's.
When using O42 curve track please note that the K-line version is 1/2 inch longer than Lionel's.
As a side note, K-line's O42 track has 4 ties, Lionel's have 3."
