When extracting reads aligned to a certain region, what is the difference between using samtools view and bamtools filter region?

Here is the code and the counts of the number of reads recovered. I don't understand why the number of reads recovered are so different between the two approaches. Any help??

```
samtools index IV75_realigned_reads.bam
samtools view -hb IV75_realigned_reads.bam 3R:15,000,000-15,100,000 > Control_region.bam
bamtools count -in Control_region.bam
# 28034
bamtools filter -region 3R:15,000,000-15,100,000 -in IV75_realigned_reads.bam -out test.bam
bamtools count -in test.bam
# 7523775
```
as far as I can read in the manual of bamtools, region are defined with two dots and not using a hyphen. You should try (and don't play with fire, remove the commas):

    3R:15000000..15100000

> REGION string format: A proper REGION string can be formatted like any of the following
examples (where 'chr1' is the name of a reference (not its ID)and '' is any valid integer position
within that reference.):  
> -region chr1  
> only alignments on (entire) reference 'chr1'  
> -region chr1:500  
> only alignments overlapping the region starting at chr1:500 and continuing to the end of chr1  
> -region chr1:500..1000  
> only alignments overlapping the region starting at chr1:500 and continuing to chr1:1000  
> -region chr1:500..chr3:750  
> only alignments overlapping the region starting at chr1:500 and continuing to chr3:750. T
