The phrase "are less extensive than" is correct and usable in written English.
It can be used to compare the extent or scope of two subjects, indicating that one is not as extensive as the other.
Example: "The resources available for this project are less extensive than those for the previous one."
Alternatives: "are not as comprehensive as" or "are more limited than".
Social services are less extensive than during the last period of double-digit unemployment, in the early 1980s.
Mr. Curtis's remarks may help explain recent reports by both Iraqi officials and American authorities that losses at the National Museum are less extensive than previously feared.
However, most of the gene expansions in Oltmannsiellopsis are less extensive than those in Pseudendoclonium; only cemA displays a longer coding sequence than its Pseudendoclonium homologue.
The elevation of GC3s near the telomeres is not restricted to subtelomeric gene families (which are less extensive than in S. cerevisiae; van het Hoog et al. 2007) but extends well into chromosomal regions that contain single-copy genes with conserved synteny in other Candida species.
The breach will eventually turn out to have been less extensive than at first feared.
But Mr. Kellner said that when the tally sheets in all five boroughs had been reviewed, the problem was less extensive than first thought.
Coverage under Mr. Baucus's plan would, by some measures, be less extensive than the least generous of three levels envisioned in a bill approved by three House committees.
Ximenes reckoned to produce about one a year, I seem to recall, but then his repertoire was less extensive than mine.
An interim pact, he said, could take the form of a memorandum of understanding and related documents, which would be less extensive than a formal security agreement.
Benning also said the Sussex operation – which planning documents show involves five ponds, two for the sturgeon – would be less extensive than the existing one in Devon.
