Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
Atlas of Peculiar Galaxies
Table title:
Material emanating from elliptical galaxies
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Arp Number </th><th colspan=1 rowspan=1 > Common Name </th><th colspan=1 rowspan=1 > Notes </th></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 137 </td><td class="highlighted"  colspan=1 rowspan=1 > NGC 2914 </td><td class="highlighted"  colspan=1 rowspan=1 > Spiral galaxy with faint spiral arms </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 138 </td><td class="highlighted"  colspan=1 rowspan=1 > NGC 4015 </td><td class="highlighted"  colspan=1 rowspan=1 > Interacting pair of galaxies </td></tr>
<tr> <td colspan=1 rowspan=1 > 139 </td><td colspan=1 rowspan=1 > Arp 139 </td><td colspan=1 rowspan=1 > Interacting pair of galaxies </td></tr>
<tr> <td colspan=1 rowspan=1 > 140 </td><td colspan=1 rowspan=1 > NGC 274, NGC 275 </td><td colspan=1 rowspan=1 > Interacting pair of galaxies </td></tr>
<tr> <td colspan=1 rowspan=1 > 141 </td><td colspan=1 rowspan=1 > UGC 3730 </td><td colspan=1 rowspan=1 > Ring galaxy system </td></tr>
<tr> <td colspan=1 rowspan=1 > 142 </td><td colspan=1 rowspan=1 > NGC 2936, NGC 2937, UGC 5130 </td><td colspan=1 rowspan=1 > Galaxy triplet </td></tr>
<tr> <td colspan=1 rowspan=1 > 143 </td><td colspan=1 rowspan=1 > NGC 2444, NGC 2445 </td><td colspan=1 rowspan=1 > Ring galaxy system </td></tr>
<tr> <td colspan=1 rowspan=1 > 144 </td><td colspan=1 rowspan=1 > NGC 7828, NGC 7829 </td><td colspan=1 rowspan=1 > Ring galaxy system </td></tr>
<tr> <td colspan=1 rowspan=1 > 145 </td><td colspan=1 rowspan=1 > UGC 1840 </td><td colspan=1 rowspan=1 > Ring galaxy system </td></tr>
</table>
Question:
What are the structural differences between NGC 2914 and NGC 4015?
Answer:
NGC 2914 (Arp 137) is a spiral galaxy with faint spiral arms and NGC 4015 (Arp 138) is an interacting pair of galaxies.