One thing the two classes share is a lack of access to Shamanic Spirit spells. In fact, only Healing and Elemental Shamans have access to them per WB15. I feel that this was an oversight, and that those spells should be able to be learned by P/A Shamans when gaining levels. At a minimum the spell Contact Spirits (8) seems appropriate.
"Plant Shamans have access to all plant spells in the Rifts series, including Biomancer spells and Nature Magic spells."-BoM pg 214
"At first level the Plant Shaman knows five Shamantic[sic] Plant spells. At second level he knows all remaining plant spells." -WB15 pg 52
Animal Shamans have nearly identical quotes.
It is ambiguous as to whether or not "all remaining plant spells" refers to only Shamanic Plant spells or all magic. This list operates under the latter. If one chooses to interpret it as the former they are encouraged to integrate the lists at the bottom of this post with those on BoM pg 210 and either 214 (Plant) or 212 (Animal), and use that for selecting spells learned upon gaining levels.
Plant: Plant Shamans gain most of their spells from Biomancy and Earth Warlock lists. One could make an argument that Invocation spells like Illusory Terrain might apply, but they are excluded below. Even though Nature Magic is specifically mentioned in BoM, there aren't many spells even arguably applicable. The ones involving food preservation focus on baked and other prepared foods, and so seem a bit a bit out of keeping with the theme.