count(*) returns different nr of rows compared to normal select

select pa.ICUSessionID,11074, obr.DateTime, obr.varvalue, true, 15001866
from tv_retrieve_observrec obr
join kd_matric.ExtrPatICUAdmissions epa on epa.PatientID = obr.admissionid
join kd_matric.PatICUAdmissions pa on pa.ICUSessionID = epa.ICUSessionID and pa.BatchID < 1152
where obr.VariableID = 15001866;

select count(*)
from tv_retrieve_observrec obr
join kd_matric.ExtrPatICUAdmissions epa on epa.PatientID = obr.admissionid
join kd_matric.PatICUAdmissions pa on pa.ICUSessionID = epa.ICUSessionID and pa.BatchID < 1152
where obr.VariableID = 15001866;