Hi Karen –
Although April is indeed the beginning of Spring in Switzerland, since it is upside down compared to New Zealand, the strong evidences of Spring will only be present at lower altitudes, including Sigriswil at about 800 meters elevation.
http://www.myswissalps.com/be sttimetovisit
In the high Alps, such as Kleine Scheidegg (KS) at 2061 meters, there will be snow on the ground early in the month, although the ski season is almost finished. High trails will be blocked until mid-June, and in most years, even early June offers very little in the way of hiking near KS.
Many but not all cableways, restaurants, hotels take between-seasons break from early April until late May or early June. Tourist density is much lower than in the rest of the year. The cograil to KS and Jungfraujoch will be running.
An example – the cableway from Wengen to Männlichen will be closed from about April 1 to mid-May, with weekend service in mid -May and full service resuming in late May.
This link is for 2018, but 2019 will be similar:
http://www.maennlichen.ch/en/ home.html
Probably, the most likely reason that Sigriswil offers cheaper accommodation is that the view from the towns on the other side of the lake is better and will show more of the famous mountains of the Jungfrau region.
If you turn on “Traffic” in the menus under Points of Interest in this map, when it is zoomed in to zoom leve 32, public transport stops become visible as icons, which provide some detaila as you mouuse over them or click on them.
map.search.ch/?pos=622640,173328&z=32 &poi=bergbahn,halteste lle,zug
In particular, that is a way to get the exact official name for every transport stop in Switzerland. That is particularly useful when you are looking a transit stops in cites, or stops with similar names in the Alps.
Then, you’ll have the exact name to enter into the timetable when you use it for anything more than the main city and town stops.
I have enjoyed many trips to Switzerland in April, but have spent my time in the lower altitudes and sunny locations such as Montreux and Weggis.
Slowpoke