bina, there are many different kinds of "smart". I have an EG ds who does not appear "quick" at anything and who doesn't look obviously intellectually gifted until you take the time to listen to his ideas. I also have a dd who doesnt test as highly gifted but who has an extremely high working memory and processing speed and she's the child that everyone else in the whole right away thinks is EG - and she's the child who more naturally performs exceptionally well at school.
While its possible that your dd's IQ score may have been underestimated, if you eventually find out it wasn't, don't *not* advocate for challenge for her or look at two children as one more "gifted" than the other -keep them both challenged and nurture their individual strengths. Parents here incur school district also sometimes are able to successfully advocate for entry into gifted programs based on achievement scores. I've seen both the pros and cons of that - it means that there are kids in class with my ds share nowhere near as high-level on eir thinking processes, but it also means kids like my high-achieving dd have opportunities to be more appropriately challenged in school than they would be otherwise. Of all three of my children, it's my closer to average range IQ kid who has the most motivati to d well in schoo and who is in fact extremely successful in school, so don't be discouraged by a not-quite-sky-high IQ result. I beleive all three of my children, each with differing abilities, will be successful and happy as adults
polarbear
