Within the Old World , the name `` martin '' tends to be used for the squarer-tailed species , and the name `` swallow '' for the more fork-tailed species ; however , there is no scientific distinction between these two groups .
Within the swallow , the name `` martin '' tends to be used for the squarer-tailed species , and the name `` swallow '' for the more fork-tailed species ; however , there is no scientific distinction between these two groups .